Search results for: ruthenium catalyst

Authors: Hossein Anaraki-Ardakani, Tayebe Heidari-Rakati

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An environmentally benign protocol for the one-pot, three-component synthesis of Triazolo[1,2-a]indazole-1,3,8-trione derivatives by condensation of dimedone, urazole and aromatic aldehydes catalyzed by HClO4/SiO2 NPS as an ecofriendly catalyst with high catalytic activity and reusability at 100 ºC under solvent-free conditions is reported. The reaction proceeds to completion within 20-30 min in 77-86 % yield.

Keywords: one-pot reaction, dimedone, triazoloindazole, urazole

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Authors: Friday Godwin Okibe, Elaoyi David Paul, Oladayo Thomas Ojekunle

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In this study, Nitrogen and Phosphorous co-doped Zinc Oxide (NPZ) was prepared through a solvent-free reaction. The NPZ was characterized by Scanning Electron Microscopy (SEM) and Fourier Transform Infrared (FTIR) spectroscopy. The photocatalytic activity of the catalyst was investigated by monitoring the degradation of para-nitrophenol (PNP) under visible light irradiation and the process was optimized using factorial design of experiment. The factors investigated were initial concentration of para-nitrophenol, catalyst loading, pH and irradiation time. The characterization results revealed a successful doping of ZnO by nitrogen and phosphorus and an improvement in the surface morphology of the catalyst. The photo-catalyst exhibited improved photocatalytic activity under visible light by 73.8%. The statistical analysis of the optimization result showed that the model terms were significant at 95% confidence level. Interactions plots revealed that irradiation time was the most significant factor affecting the degradation process. The cube plots of the interactions of the variables showed that an optimum degradation efficiency of 66.9% was achieved at 10mg/L initial PNP concentration, 0.5g catalyst loading, pH 7 and 150 minutes irradiation time.

Keywords: nitrogen and phosphorous co-doped Zno, p-nitrophenol, photocatalytic degradation, optimization, factorial design of experimental

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Authors: Angga Pratama Herman, Muhammad Shahbaz, Suzana Yusup

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Bottom ash is a solid waste from thermal power plant and it is usually disposed of into landfills and ash ponds. These disposal methods are not sustainable since new lands need to be acquired as the landfills and ash ponds are fill to its capacity. Bottom ash also classified as hazardous material that makes the disposal methods may have contributed to the environmental effect to the area. Hence, more research needs to be done to explore the potential of recycling the bottom ash as more useful product. The objective of this research is to explore the potential of utilizing bottom ash as catalyst in biomass steam gasification. In this research, bottom ash was used as catalyst in gasification of Palm Kernel Shell (PKS) using Thermo Gravimetric Analyzer coupled with mass spectrometry (TGA/MS). The effects of temperature (650 – 750 °C), particle size (0.5 – 1.0 mm) and bottom ash percentage (2 % - 10 %) were studied with and without steam. The experimental arrays were designed using expert method of Central Composite Design (CCD). Results show maximum yield of hydrogen gas was 34.3 mole % for gasification without steam and 61.4 Mole % with steam. Similar trend was observed for syngas production. The maximum syngas yield was 59.5 mole % for without steam and it reached up to 81.5 mole% with the use of steam. The optimal condition for both product gases was temperature 700 °C, particle size 0.75 mm and cool bottom ash % 0.06. In conclusion, the use of bottom ash as catalyst is possible for biomass steam gasification and the product gases composition are comparable with previous researches, however the results need to be validated for bench or pilot scale study.

Keywords: bottom ash, biomass steam gasification, catalyst, lab scale

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Authors: D. M. Reddy Prasad, Nur Sabrina Binti Rahmat, Huei Ruey Ong, Chin Kui Cheng, Maksudur Rahman Khan, D. Sathiyamoorthy

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Carbon dioxide (CO₂) emission to the environment is inevitable which is responsible for global warming. Photocatalytic reduction of CO₂ to fuel, such as methanol, methane etc. is a promising way to reduce greenhouse gas CO₂ emission. In the present work, Bi₂S₃/CdS was synthesized as an effective visible light responsive photocatalyst for CO₂ reduction into methanol. The Bi₂S₃/CdS photocatalyst was prepared by hydrothermal reaction. The catalyst was characterized by X-ray diffraction (XRD) instrument. The photocatalytic activity of the catalyst has been investigated for methanol production as a function of time. Gas chromatograph flame ionization detector (GC-FID) was employed to analyze the product. The yield of methanol was found to increase with higher CdS concentration in Bi₂S₃/CdS and the maximum yield was obtained for 45 wt% of Bi₂S₃/CdS under visible light irradiation was 20 μmole/g. The result establishes that Bi₂S₃/CdS is favorable catalyst to reduce CO₂ to methanol.

Keywords: photocatalyst, CO2 reduction, methanol, visible light, XRD, GC-FID

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Authors: Jafar Akbari

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Quinolines are very important compounds partially because of their pharmacological properties which include wide applications in medicinal chemistry. notable among them are antimalarial drugs, anti-inflammatory agents, antiasthamatic, antibacterial, antihypertensive, and tyrosine kinase inhibiting agents. Despite quinoline usage in pharmaceutical and other industries, comparatively few methods for their preparation have been reported.The Friedlander annulation is one of the simplest and most straightforward methods for the synthesis of poly substituted quinolines. Although, modified methods employing lewis or br¢nsted acids have been reported for the synthesis of quinolines, the development of water stable acidic catalyst for quinoline synthesis is quite desirable. One of the most remarkable features of ionic liquids is that the yields can be optimized by changing the anions or the cations. Recently, sulfonic acid functionalized ionic liquids were used as solvent-catalyst for several organic reactions. We herein report the one pot domino approach for the synthesis of quinoline derivatives in Friedlander manner using TSIL as a catalyst. These ILs are miscible in water, and their homogeneous system is readily separated from the reaction product, combining advantages of both homogeneous and heterogeneous catalysis. In this reaction, the catalyst plays a dual role; it ensures an effective condensation and cyclization of 2-aminoaryl ketone with second carbonyl group and it also promotes the aromatization to the final product. Various types of quinolines from 2-aminoaryl ketones and β-ketoesters/ketones were prepared in 85-98% yields using the catalytic system of SO3-H functionalized ionic liquid/H2O. More importantly, the catalyst could be easily recycled for five times without loss of much activity.

Keywords: antimalarial drugs, green chemistry, ionic liquid, quinolines

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Authors: Hossein Anaraki-Ardakani

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A green and efficient one-pot synthesis of benzylamino coumarin derivatives by a three-component condensation of 4-hydroxycoumarin, cyclic secondary amine, and aromatic aldehyde in the presence of ZrO2 nanoparticles (NPs) as a heterogeneous catalyst in water at room temperature has been reported.

Keywords: 3-benzyl substituted coumarin derivative, ZrO2 nanoparticles (NPs), green synthesis, multicomponent reaction

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Authors: Ya-Ting Liao, Chien-Chang Huang

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Green diesel is a renewable biofuel obtained from plant oil or fatty acid deoxygenation. Because the molecular structure of green diesel is similar to that of fossil fuel, green diesel can be directly used in present vehicle engines without blending with fossil fuel. In this study, mesoporous carbon-based catalysts with doped metal ions, such as Mg, Ni, or Fe, were prepared using co-polymers and gallic acid as molecular templates and carbon sources, respectively. The prepared catalysts were then applied to carry out the deoxygenation of fatty acid and waste cooking oil. To obtain the highest net energy from the produced green diesel, the catalyzed deoxygenation reaction and catalyst preparation processes were carried out under ambient conditions, respectively, to avoid using H₂ as a reagent and reducing agent. XRD, BET, SEM, EDS, FT-IR, and pyridine-IR characterized the composition and configuration of the prepared catalyst. The results display that the doped metal ions were well-dispersed in the carbon-based catalyst and the surface of the catalysts was rich in Lewis acid sites after the catalysts were calcined at the proper temperature. The pore size present on the catalyst was 9-11 nm. To catalyze the deoxygenation of fatty acid by the prepared catalysts at 320℃ under H₂-free conditions, high fatty acid conversion (99%) and high selectivity for hydrocarbons (78%) were obtained when the ratio of doped Ni to doped Mg was optimized.

Keywords: ordered mesoporous carbon, catalysts, hydrocarbons, deoxygenation

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Authors: Abolfazl Bezaatpour, Sahar Khatami

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Fe3O4 nanoparticles were prepared by the co-precipitation method and silica was then coated on the magnetic nanoparticles followed by modification with (3-aminopropyl) trimethoxysilane. Then, dioxomolybdenum(VI) Schiff base complex of N,N′-bis(5-chloromethyl-salicylidine)-1,2-phenylenediamine) was immobilized on the surface of magnetic nanoparticles as a heterogeneous catalyst. The catalyst was identified by scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM), X-ray diffraction, IR spectroscopy, diffuse reflectance spectra and atomic absorption spectroscopy techniques. The catalyst shows excellent catalytic activity in epoxidation of olefins using tert-butylhydroperoxide in 1,2-dichloroethane. In this report, the supported complex exhibited 100% selectivity for epoxidation with 100% conversion for cyclooctene. Nanocatalyst can be easily recovered by a magnetic field and reused for subsequent reactions for at least 5 times with less deterioration in catalytic activity.

Keywords: dioxomolybdenum (VI), epoxidation, nanocatalysis, nanoparticles, Schiff base

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Authors: Sushil Kumar Saraswat, K. K. Pant

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Co metal supported on SiO2 and Al2O3 catalysts with a metal loading varied from 30 of 70 wt.% were evaluated for decomposition of methane to CO/CO2 free hydrogen and carbon nano materials. The catalytic runs were carried out from 550-800 oC under atmospheric pressure using fixed bed vertical flow reactor. The fresh and spent catalysts were characterized by BET surface area analyzer, TPR, XRD, SEM, TEM, and TG analysis. The data showed that 50% Co/Al2O3 catalyst exhibited remarkable higher activity and stability up to 10 h time-on-stream at 750 oC with respect to H2 production compared to rest of the catalysts. However, the catalytic activity and durability was greatly declined at a higher temperature. The main reason for the catalytic inhibition of Co containing SiO2 catalysts is the higher reduction temperature of Co2SiO4. TEM images illustrate that the carbon materials with various morphologies, carbon nanofibers (CNFs), helical-shaped CNFs, and branched CNFs depending on the catalyst composition and reaction temperature, were obtained. The TG data showed that a higher yield of MWCNTs was achieved over 50% Co/Al2O3 catalyst compared to other catalysts.

Keywords: carbon nanotubes, cobalt, hydrogen production, methane decomposition

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Authors: S. F. H. Tasfy, N. A. M. Zabidi, M.-S. Shaharun

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Utilization of CO2 as a carbon source to produce valuable chemicals is one of the important ways to reduce the global warming caused by increasing CO2 in the atmosphere. Supported metal catalysts are crucial for the production of clean and renewable fuels and chemicals from the stable CO2 molecules. The catalytic conversion of CO2 into methanol is recently under increased scrutiny as an opportunity to be used as a low-cost carbon source. Therefore, series of the bimetallic Cu/ZnO-based catalyst supported by SBA-15 were synthesized via impregnation technique with different total metal loading and tested in the catalytic hydrogenation of CO2 to methanol. The morphological and textural properties of the synthesized catalysts were determined by transmission electron microscopy (TEM), temperature programmed desorption, reduction, oxidation and pulse chemisorption (TPDRO), and N2-adsorption. The CO2 hydrogenation reaction was performed in microactivity fixed-bed system at 250 °C, 2.25 MPa, and H2/CO2 ratio of 3. Experimental results showed that the catalytic structure and performance was strongly affected by the loading of the active site. Where, the catalytic activity, methanol selectivity as well as the space-time yield increased with increasing the metal loading until it reaches the maximum values at a metal loading of 15 wt% while further addition of metal inhibits the catalytic performance. The higher catalytic activity of 14 % and methanol selectivity of 92 % were obtained over Cu/ZnO-SBA-15 catalyst with total bimetallic loading of 15 wt%. The excellent performance of 15 wt% Cu/ZnO-SBA-15 catalyst is attributed to the presence of well disperses active sites with small particle size, higher Cu surface area, and lower catalytic reducibility.

Keywords: hydrogenation of carbon dioxide, methanol synthesis, metal loading, Cu/ZnO-SBA-15 catalyst

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Authors: Draoua Zohra, Harrane Amine

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The Solid Polymeric Materials have been successfully prepared by the copolymerization of e-caprolactone (CL) and poly (ethylene glycol) (PEG) employing Maghnite-H+ at 80°C. Maghnite-H+ is a solid catalyst non-toxic. The presence of PEG chains leads to a break in the growth of PCL chains and consequently leads to the copolymer tri-block PCL-PEG-PCL. The objective of this study was to synthesize and characterize of Solid Polymeric Materials. The highly hydrophilic nature of polyethylene glycol has sparked our interest in developing a Solid Polymeric based e-caprolactone and poly (ethylene glycol). PCL and PEG are biocompatible materials. Their ring-opening copolymerization using Maghnite H+ makes to the Solid Polymeric Materials. The morphology and structure of Solid polymeric Materials were characterized by ¹H and ¹³C-NMR spectra and Gel Permeation Chromatography (GPC). This paper developed the application of Maghnite-H+ as an efficient catalyst by an easy-to-handle procedure to get solid polymeric materials. A cationic mechanism for the copolymerization reaction was proposed.

Keywords: block copolymers, maghnite, montmorillonite, poly(e-caprolactone)

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Authors: Sony, Ashok N. Bhaskarwar

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Production of hydrogen from a renewable raw material without any co-synthesis of harmful greenhouse gases is the current need for sustainable energy solutions. The sulfur-iodine (SI) thermochemical cycle, using intermediate chemicals, is an efficient process for producing hydrogen at a much lower temperature than that required for the direct splitting of water. No net byproduct forms in the cycle. Hydrogen iodide (HI) decomposition is a crucial reaction in this cycle, as the product, hydrogen, forms only in this step. It is an endothermic, reversible, and equilibrium-limited reaction. The theoretical equilibrium conversion at 550°C is just a meagre of 24%. There is a growing interest, therefore, in enhancing the HI conversion to near-equilibrium values at lower reaction temperatures and by possibly improving the rate. The reaction is relatively slow without a catalyst, and hence catalytic decomposition of HI has gained much significance. Bi-metallic Ni-Co, Ni-Mn, Co-Mn, and tri-metallic Ni-Co-Mn catalysts over zirconia support were tested for HI decomposition reaction. The catalysts were synthesized via a sol-gel process wherein Ni was 3wt% in all the samples, and Co and Mn had equal weight ratios in the Co-Mn catalyst. Powdered X-ray diffraction and Brunauer-Emmett-Teller surface area characterizations indicated the polycrystalline nature and well-developed mesoporous structure of all the samples. The experiments were performed in a vertical laboratory-scale packed bed reactor made of quartz, and HI (55 wt%) was fed along with nitrogen at a WHSV of 12.9 hr⁻¹. Blank experiments at 500°C for HI decomposition suggested conversion of less than 5%. The activities of all the different catalysts were checked at 550°C, and the highest conversion of 23.9% was obtained with the tri-metallic 3Ni-Co-Mn-ZrO₂ catalyst. The decreasing order of the performance of catalysts could be expressed as: 3Ni-Co-Mn-ZrO₂ > 3Ni-2Co-ZrO₂ > 3Ni-2Mn-ZrO₂ > 2.5Co-2.5Mn-ZrO₂. The tri-metallic catalyst remained active till 360 mins at 550°C without any observable drop in its activity/stability. Among the explored catalyst compositions, the tri-metallic catalyst certainly has a better performance for HI conversion when compared to the bi-metallic ones. Owing to their low costs and ease of preparation, these trimetallic catalysts could be used for large-scale hydrogen production.

Keywords: sulfur-iodine cycle, hydrogen production, hydrogen iodide decomposition, bi-, and tri-metallic catalysts

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Authors: Deepti Mishra, Arindam Modak, K. K. Pant, Xiu Song Zhao

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The promotional effect of mixed ceria-zirconia oxides (CZO) over the Mo/HZSM-5 catalyst for methane dehydroaromatization (MDA) reaction was studied. The surface and structural properties of the synthesized catalyst were characterized using a range of spectroscopic and microscopic techniques, and the correlation between catalytic properties and its performance for MDA reaction is discussed. The impregnation of CZO solid solution on Mo/HZSM-5 was observed to give an excellent catalytic performance and improved benzene formation rate (4.5 μmol/gcat. s) as compared to the conventional Mo/HZSM-5 (3.1 μmol/gcat. s) catalyst. In addition, a significant reduction in coke formation was observed in the CZO-modified Mo/HZSM-5 catalyst. The prevailing comprehension for higher catalytic activity could be because of the redox properties of CZO deposited Mo/HZSM-5, which acts as a selective oxygen supplier and performs hydrogen combustion during the reaction, which is indirectly probed by O₂-TPD and H₂-TPR analysis. The selective hydrogen combustion prevents the over-oxidation of aromatic species formed during the reaction while the generated steam helps in reducing the amount of coke generated in the MDA reaction. Thus, the advantage of CZO incorporated Mo/HZSM-5 is manifested as it promotes the reaction equilibrium to shift towards the formation of benzene which is favourable for MDA reaction.

Keywords: Mo/HZSM-5, ceria-zirconia (CZO), in-situ combustion, methane dehydroaromatization

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Authors: Thomas Chinedu Aniokete, Gordian Onyebuchukwu Mbah, Michael Daramola

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A sustainable NaOH integrated hydrothermal protocol was developed for the synthesis of waste-derived hydroxy sodalite catalysts for transesterification of waste animal fat (WAF) with a high per cent free fatty acid (FFA) to biodiesel. In this work, hydroxy sodalite catalyst was synthesized from two complex waste materials namely coal fly ash (CFA) and waste industrial brine (WIB). Measured amounts of South African CFA and WIB obtained from a coal mine field were mixed with NaOH solution at different concentrations contained in secured glass vessels equipped with magnetic stirrers and formed consistent slurries after aging condition at 47 oC for 48 h. The slurries were then subjected to hydrothermal treatments at 140 oC for 48 h, washed thoroughly and separated by the action of a centrifuge on the mixture. The resulting catalysts were calcined in a muffle furnace for 2 h at 200 oC and subsequently characterized for different effects using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), and Bennett Emmet Teller (BET) adsorption-desorption techniques. The produced animal fat methyl ester (AFME) was analyzed using the gas chromatography-mass spectrometry (GC-MS) method. Results of the investigation indicate profoundly an enhanced catalyst purity, textural property and desired morphology due to the action of NaOH. Similarly, the performance evaluation with respect to catalyst activity reveals a high catalytic conversion efficiency of 98 % of the high FFA WAF to biodiesel under the following reaction conditions; a methanol-to-WAF ratio of 15:1, amount of SOD catalyst of 3 wt % with a stirring speed of 300-500 rpm, a reaction temperature of 60 oC and a reaction time of 8 h. There was a recovered 96 % stable catalyst after reactions and potentially recyclable, thus contributing to the economic savings to the process that had been a major bottleneck to the production of biodiesel. This NaOH route for synthesizing waste-derived hydroxy sodalite (SOD) catalyst is a sustainable and eco-friendly technology that speaks directly to the global quest for renewable-fossil fuel controversy enforcing sustainable development goal 7.

Keywords: coal fly ash, waste industrial brine, waste-derived hydroxy sodalite catalyst, sodium hydroxide, biodiesel, transesterification, biomass conversion

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Authors: Joy Marie Mora, Mark Daniel De Luna, Tsair-Wang Chung

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Transesterification reaction of soybean oil with methanol was carried out to produce fatty acid methyl esters (FAME) using calcined alkali metal (Na and Li) supported by pumice silica as the solid base catalyst. Pumice silica catalyst was activated by loading alkali metal ions to its surface via an ion-exchange method. Response surface methodology (RSM) in combination with Box-Behnken design (BBD) was used to optimize the operating parameters in biodiesel production, namely: reaction temperature, methanol to oil molar ratio, reaction time, and catalyst concentration. Using the optimized sets of parameters, FAME yields using sodium and lithium silicate catalysts were 98.80% and 98.77%, respectively. A pseudo-first order kinetic equation was applied to evaluate the kinetic parameters of the reaction. The prepared catalysts were characterized by several techniques such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Brunauer-Emmett-Teller (BET) sorptometer, and scanning electron microscopy (SEM). In addition, the reusability of the catalysts was successfully tested in two subsequent cycles.

Keywords: alkali metal, biodiesel, Box-Behnken design, heterogeneous catalyst, kinetics, optimization, pumice, transesterification

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Authors: Brenda Cecilia Ledesma, Andrea Beltramone

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This work deals with the bio-waste valorization approach for catalyst development, the use of products derived from biomass as raw material and the obtaining of biofuels. In this research, activated carbons were synthesized from the orange peel using different synthesis conditions. With the activated carbons obtained with the best structure and texture, PtIr bimetallic catalysts were prepared. Carbon activation was carried out through a chemical process with phosphoric acid as an activating agent, varying the acid concentration, the ratio substrate/activating agent and time of contact between them. The best support was obtained using a carbonization time of 1 h, the temperature of carbonization of 470oC, the phosphoric acid concentration of 50 wt.% and a BET area of 1429 m2/g. Subsequently, the metallic nanoparticles were deposited in the activated carbon to use the solid as a catalytic material for the hydrogenation of HMF to 2,5-DMF. The catalyst presented an excellent performance for biofuels generation.

Keywords: orange peel, bio-waste valorization, platinum, iridium, 5-hydroxymethylfurfural

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Authors: Nadeem Bashir, Ghulam Mustafa Peerzada

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The present study pertains to the nonlinear behavior of acetaminophen based uncatalyzed Belousov-Zhabotinsky (BZ) oscillator and its dynamics in the presence of Ferroin as the catalyst. The role of free metal ions as catalysts was examined and the results compared with corresponding complexed catalysts. Free metal ions were found to be sluggish with respect to the evolution of the oscillatory regime as compared to complexed ones. Effect of change of the ligand moiety of the catalyst complex on the oscillatory parameters was monitored. Since ethanol potentiates the hepatotoxicity caused by acetaminophen in-vivo, it is thought to understand this interaction by virtue of causing perturbation of the acetaminophen based oscillator with different concentrations of the ethanol with and without ferroin as the catalyst. Another dimension to the ethanol effect was added by perturbation of the system with ethanol at different stages of the reaction so as to get an idea whether it is acetaminophen or some reactive intermediate generated in the reaction system which reacts with ethanol. Further, the ferroin-catalyzed oscillator is taken as a prototype inorganic model of the acetaminophen-ethanol syndrome, as ferroin and HOBr were inorganic replacements to Cyt P450 and NADPH in the alcohol metabolism.

Keywords: Belousov-Zhabotinsky reaction, ferroin, Paracetamol-Ethanol syndrome, kinetics

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Authors: Swarnalata Sahoo, Smita Mohanty, S. K. Nayak

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Environmentally friendly Polyurethane(PU) synthesis from Castor oil(CO) has been studied extensively. Probably due to high proportion of fatty hydroxy acids and unsaturated bond, CO showed better performance than other oil, can be easily utilized as commercial applications. In this work, cured PU polymers having different –NCO/OH ratio with and without catalyst were synthesized by using partially biobased Isocyanate with castor oil (CO). Curing time has been studied by observing at the time of reaction, which can be confirmed by AT-FTIR. DSC has been studied to monitor the reaction between CO & Isocyanates using non Isothermal process. Curing kinetics have also been studied to investigate the catalytic effect of the NCO / OH ratio of Polyurethane. Adhesion properties were evaluated from Lapshear test. Tg of the PU polymer was evaluated by DSC which can be compared by DMA. Surface Properties were studied by contact angle measurement. Improvement of the interfacial adhesion between the nonpolar surface of Aluminum substrate and the polar adhesive has been studied by modifying surface.

Keywords: polyurethane, partially bio-based isocyanate, castor oil, catalyst

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Authors: S. Said, Asmaa A. Abdulrahman

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MoOₓ/Al₂O₃ based catalyst has long been widely used as an active catalyst in oxidative desulfurization reaction due to its high stability under severe reaction conditions and high resistance to sulfur poisoning. In this context, 4 & 9wt.% MoO₃ grafted on mesoporous γ-Al₂O₃ has been synthesized using the modified atomic layer deposition (ALD) method. Another MoO₃/Al₂O₃ sample was prepared by the conventional wetness impregnation (IM) method, for comparison. The effect of the preparation methods on the metal-support interaction was evaluated using different characterization techniques, including X-ray diffraction, X-ray photoelectron spectroscopy (XPS), N₂-physisorption, transmission electron microscopy (TEM), H₂- temperature-programmed reduction and FT-IR. Oxidative desulfurization (ODS) reaction of the model fuel oil was used as a probe reaction to examine the catalytic efficiency of the prepared catalysts. ALD method led to samples with much better physicochemical properties than those of the prepared one via the impregnation method. However, the 9 wt.%MoO₃/Al₂O₃ (ALD) catalyst in the ODS reaction of model fuel oil shows enhanced catalytic performance with ~90%, which has been attributed to the more Mo⁶⁺ surface concentrations relative to Al³⁺ with large pore diameter and surface area. The kinetic study shows that the ODS of DBT follows a pseudo first-order rate reaction.

Keywords: mesoporous Al₂O₃, xMoO₃/Al₂O₃, atomic layer deposition, wetness impregnation, ODS, DBT

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Authors: Pauline Bredy, Yves Schuurman, David Farrusseng

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To fulfill climate objectives, the production of synthetic e-fuels using CO₂ as a raw material appears as part of the solution. In particular, Power-to-Liquid (PtL) concept combines CO₂ with hydrogen supplied from water electrolysis, powered by renewable sources, which is currently gaining interest as it allows the production of sustainable fossil-free liquid fuels. The proposed process discussed here is an upgrading of the well-known Fischer-Tropsch synthesis. The concept deals with two cascade reactions in one pot, with first the conversion of CO₂ into CO via the reverse water gas shift (RWGS) reaction, which is then followed by the Fischer-Tropsch Synthesis (FTS). Instead of using a Fe-based catalyst, which can carry out both reactions, we have chosen the strategy to decouple the two functions (RWGS and FT) on two different catalysts within the same reactor. The FTS shall shift the equilibrium of the RWGS reaction (which alone would be limited to 15-20% of conversion at 250°C) by converting the CO into hydrocarbons. This strategy shall enable optimization of the catalyst pair and thus lower the temperature of the reaction thanks to the equilibrium shift to gain selectivity in the liquid fraction. The challenge lies in maximizing the activity of the RWGS catalyst but also in the ability of the FT catalyst to be highly selective. Methane production is the main concern as the energetic barrier of CH₄ formation is generally lower than that of the RWGS reaction, so the goal will be to minimize methane selectivity. Here we report the study of different combinations of copper-based RWGS catalysts with different cobalt-based FTS catalysts. We investigated their behaviors under mild process conditions by the use of high-throughput experimentation. Our results show that at 250°C and 20 bars, Cobalt catalysts mainly act as methanation catalysts. Indeed, CH₄ selectivity never drops under 80% despite the addition of various protomers (Nb, K, Pt, Cu) on the catalyst and its coupling with active RWGS catalysts. However, we show that the activity of the RWGS catalyst has an impact and can lead to longer hydrocarbons chains selectivities (C₂⁺) of about 10%. We studied the influence of the reduction temperature on the activity and selectivity of the tandem catalyst system. Similar selectivity and conversion were obtained at reduction temperatures between 250-400°C. This leads to the question of the active phase of the cobalt catalysts, which is currently investigated by magnetic measurements and DRIFTS. Thus, in coupling it with a more selective FT catalyst, better results are expected. This was achieved using a cobalt/iron FTS catalyst. The CH₄ selectivity dropped to 62% at 265°C, 20 bars, and a GHSV of 2500ml/h/gcat. We propose that the conditions used for the cobalt catalysts could have generated this methanation because these catalysts are known to have their best performance around 210°C in classical FTS, whereas the iron catalysts are more flexible but are also known to have an RWGS activity.

Keywords: cobalt-copper catalytic systems, CO₂-hydrogenation, Fischer-Tropsch synthesis, hydrocarbons, low-temperature process

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Authors: Allah Bakhsh Javid, Ali Mashayekh-Salehi, Fatemeh Davardoost

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This study presents the preparation, characterization and catalytic activity of a novel natural mineral-based catalyst for destructive adsorption of tetracycline (TTC) as water emerging compounds. Degradation potential of raw and calcined magnetite catalyst was evaluated at different experiments situations such as pH, catalyst dose, reaction time and pollutant concentration. Calcined magnetite attained greater catalytic potential than the raw ore in the degradation of tetracycline, around 69% versus 3% at reaction time of 30 min and TTC aqueous solution of 50 mg/L, respectively. Complete removal of TTC could be obtained using 2 g/L calcined nanoparticles at reaction time of 60 min. The removal of TTC increased with the increase in solution temperature. Accordingly, considering its abundance in nature together with its very high catalytic potential, calcined pyrite is a promising and reliable catalytic material for destructive decomposition for catalytic decomposition and mineralization of such pharmaceutical compounds as TTC in water and wastewater.

Keywords: catalytic degradation, tetracycline, pyrite, emerging pollutants

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Authors: Zohreh Derikvand

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Nanoreactors Zr-MCM-41were prepared via the reaction of ZrOCl2, Fumed silica, sodium hydroxide and cethyltrimethyl ammonium bromide under hydrothermal condition. The prepared nanoreactors were characterized by FT-IR spectroscopy, X-ray diffraction (XRD), Scanning electron micrographs (SEM) and nitrogen adsorption-desorption. The XRD pattern of Zr-MCM-41 exhibits a high-intensity (100) and two low-intensity reflections (110 and 200) which are characteristic of hexagonal structure, exhibiting the long-range order and good textural uniformity of mesoporous structure. Based on the green chemistry approach, we report an efficient and environmentally benign protocol to study the catalytic activity of Zr-MCM-41 in the Biginelli type reactions initially. Nanoreactors Zr-MCM-41 were used as highly recoverable and reusable catalyst for synthesis of 3,4-dihydropyrimidin-2(1H)-one, octahydroquinazolinone, benzimidazolo-quinazolineone and 4,6-diarylpyrimidin-2(1H)-one. The methodology offers several advantages such as short reaction time, high yields and simple operation. The catalyst was active up to three cycles.

Keywords: Zr-MCM-41 nanoreactors, Biginelli like reactions, 3, 4-dihydropyrimidin-2(1H)-ones, ctahydroquinazolinones

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Authors: Alexsandro Bayestorff da Cunha, Dpebora Caline de Mello, Camila Alves Corrêa

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In the production of fiberboards, an adhesive based on urea-formaldehyde resin is used, which has the advantages of low cost, homogeneity of distribution, solubility in water, high reactivity in an acid medium, and high adhesion to wood. On the other hand, as a disadvantage, there is low resistance to humidity and the release of formaldehyde. The objective of the study was to determine the viability of adding industrial boiler ash to the urea formaldehyde-based adhesive for the production of medium-density fiberboard. The raw material used was composed of Pinus spp fibers, urea-formaldehyde resin, paraffin emulsion, ammonium sulfate, and boiler ash. The experimental plan, consisting of 8 treatments, was completely randomized with a factorial arrangement, with 0%, 1%, 3%, and 5% ash added to the adhesive, with and without the application of a catalyst. In each treatment, 4 panels were produced with density of 750 kg.m⁻³, dimensions of 40 x 40 x 1,5 cm, 12% urea formaldehyde resin, 1% paraffin emulsion and hot pressing at a temperature of 180ºC, the pressure of 40 kgf/cm⁻² for a time of 10 minutes. The different compositions of the adhesive were characterized in terms of viscosity, pH, gel time and solids, and the panels by physical and mechanical properties, in addition to evaluation using the IMAL DPX300 X-ray densitometer and formaldehyde emission by the perforator method. The results showed a significant reduction of all adhesive properties with the use of the catalyst, regardless of the treatment; while the percentage increase of ashes provided an increase in the average values of viscosity, gel time, and solids and a reduction in pH for the panels with a catalyst; for panels without catalyst, the behavior was the opposite, with the exception of solids. For the physical properties, the results of the variables of density, compaction ratio, and thickness were equivalent and in accordance with the standard, while the moisture content was significantly reduced with the use of the catalyst but without the influence of the percentage of ash. The density profile for all treatments was characteristic of medium-density fiberboard, with more compacted and dense surfaces when compared to the central layer. For thickness, the swelling was not influenced by the catalyst and the use of ash, presenting average values within the normalized parameters. For mechanical properties, the influence of ashes on the adhesive was negatively observed in the modulus of rupture from 1% and in the traction test from 3%; however, only this last property, in the percentages of 3% and 5%, were below the minimum limit of the norm. The use of catalyst and ashes with percentages of 3% and 5% reduced the formaldehyde emission of the panels; however, only the panels that used adhesive with catalyst presented emissions below 8mg of formaldehyde / 100g of the panel. In this way, it can be said that boiler ash can be added to the adhesive with a catalyst without impairing the technological properties by up to 1%.

Keywords: reconstituted wood panels, formaldehyde emission, technological properties of panels, perforator

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Authors: Krasimir I. Ivanov, Elitsa N. Kolentsova, Dimitar Y. Dimitrov, Georgi V. Avdeev, Tatyana T. Tabakova

Abstract:

In recent research copper and manganese systems were found to be the most active in CO and organic compounds oxidation among the base catalysts. The mixed copper manganese oxide has been widely studied in oxidation reactions because of their higher activity at low temperatures in comparison with single oxide catalysts. The results showed that the formation of spinel CuxMn3−xO4 in the oxidized catalyst is responsible for the activity even at room temperature. That is why most of the investigations are focused on the hopcalite catalyst (CuMn2O4) as the best copper-manganese catalyst. Now it’s known that this is true only for CO oxidation, but not for mixture of CO and VOCs. The purpose of this study is to investigate the alumina supported copper-manganese catalysts with different Cu/Mn molar ratio in terms of oxidation of CO, methanol and dimethyl ether. The catalysts were prepared by impregnation of γ-Al2O3 with copper and manganese nitrates and the catalytic activity measurements were carried out in continuous flow equipment with a four-channel isothermal stainless steel reactor. Gas mixtures on the input and output of the reactor were analyzed with a gas chromatograph, equipped with FID and TCD detectors. The texture characteristics were determined by low-temperature (- 196 oС) nitrogen adsorption in a Quantachrome Instruments NOVA 1200e (USA) specific surface area&pore analyzer. Thermal, XRD and TPR analyses were performed. It was established that the active component of the mixed Cu-Mn/γ–alumina catalysts strongly depends on the Cu/Mn molar ratio. Highly active alumina supported Cu-Mn catalysts for CO, methanol and DME oxidation were synthesized. While the hopcalite is the best catalyst for CO oxidation, the best compromise for simultaneous oxidation of all components is the catalyst with Cu/Mn molar ratio 1:5.

Keywords: supported copper-manganese catalysts, CO, VOCs oxidation, combustion of exhaust gases

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Authors: Corazon Virtudazo-Ligaray, Mark Daniel G. de Luna, Meng-Wei Wan, Ming-Chun Lu

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A series of ternary compound catalyst with nanocomposites of ceria, tungsten trioxide and titania (CeO2-WOx-TiO2) with different WOx mole fraction (10, 20, 30, 40) have been synthesized by sol-gel method. These nanocomposite catalysts were used for oxidative extractive desulfurization of model fuel oil, which were composed of dibenzothiophene (DBT) dissolved in toluene. The 30% hydrogen peroxide, H2O2 was used as oxidant and acetonitrile as extractant. These catalysts were characterized by SEM-EDS to determine the morphology. Catalytic oxidation results show that the catalysts have high selectivity in refractory fuel oil with organo sulfur contents. The oxidative removal of DBT increases as the HPW content increases. The nanocomposites CeO2-WOx-TiO2 also shows high selectivity for DBT oxidation in the DBT–toluene acetonitrile system. The catalytic oxidative desulfurization ratio of model fuel reached to 100% with nanocomposites CeO2-WOx-TiO2 (35-30-35) mol percent catalyst nanocomposition under 333 K in 30 minutes.

Keywords: ceria, oxidative desulfurization, titania, phosphotungstic acid

Procedia PDF Downloads 384

Authors: Y. J. Lin, Y. F. Lin

Abstract:

CO2 is the primary greenhouse gas which causes global warming in recent years. As the carbon capture and storage (CCS) getting maturing, the reuse of carbon dioxide which made from CCS is the important issue. In this way, the most common method is the synthesis of cyclic carbonate chemicals from the cycloaddition reaction of carbon dioxide and epoxide. The catalyst plays an important role in the CO2/epoxide cycloaddition reactions. The Lewis acid and base sites are both needed on the catalyst surface for the help of epoxide ring opening, leading to the synthesis of cyclic carbonate. Furthermore, the larger specific surface area and more active site of the catalyst are also needed to enhance the efficiency of the CO2/epoxide cycloaddition reactions. Aerogel is a mesoporous nanomaterial (pore size between 2~50 nm) with high specific surface area and porosity (at least 90%) and low density. In this study, the ternary metal oxide aerogels, Mg-doped Al2O3 aerogels, with higher specific surface area and Lewis acid and base sites on the aerogel surface are successfully prepared by using a facile sol-gel reaction. The as-prepared Mg-doped Al2O3 aerogels are also served as heterogenous catalyst for the CO2/propylene- oxide cycloaddition reaction. Compared to the pristine Al2O3 aerogels, the Mg-doped Al2O3 aerogels possessed both Lewis acid and base sites on the surface are able to enhance the efficiency of the CO2/propylene oxide cycloaddition reactions. As a result, the as-prepared Mg-doped Al2O3 aerogels are a promising and novel catalyst for the CO2/epoxide cycloaddition reactions.

Keywords: ternary, metal oxide aerogel, CO2 reuse, cycloaddition, propylene oxide

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Authors: Zhanzhao Fu, Chongyi Ling, Jinlan Wang

Abstract:

Water splitting and rechargeable air-based batteries are emerging as new renewable energy storage and conversion technologies. However, the discovery of suitable catalysts with high activity and low cost remains a great challenge. In this work, we report a single-atom trifunctional catalyst, namely Ti₃C₂O₂ supported single Pd atom (Pd1@Ti₃C₂O₂), for the hydrogen evolution reaction (HER), oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). This catalyst is selected from 12 candidates and possesses low overpotentials of 0.22 V, 0.31 V and 0.34 V for the HER, OER and ORR, respectively, making it an excellent electrocatalyst for both overall water splitting and rechargeable air-based batteries. The superior OER and ORR performance originates from the optimal d band center of the supported Pd atom. Moreover, the excellent activity can be maintained even if the single Pd atoms aggregate into small clusters. This work offers new opportunities for advancing the renewable energy storage and conversion technologies and paves a new way for the development of multifunctional electrocatalysts.

Keywords: DFT, SACs, OER, ORR, HER

Procedia PDF Downloads 47

Authors: N. Laosiripojana, P. Tepamatr

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The influence of bismuth on the water gas shift activities of Pt on ceria was studied. The flow reactor was used to study the activity of the catalysts in temperature range 100-400°C. The feed gas composition contains 5%CO, 10% H₂O and balance N₂. The total flow rate was 100 mL/min. The outlet gas was analyzed by on-line gas chromatography with thermal conductivity detector. The catalytic activities of bimetallic 1%Pt1%Bi/CeO₂ catalyst were greatly enhanced when compared with the activities of monometallic 2%Pt/CeO₂ catalyst. The catalysts were characterized by X-ray diffraction (XRD), Temperature-Programmed Reduction (TPR) and surface area analysis. X-ray diffraction pattern of Pt/CeO₂ and PtBi/CeO₂ indicated slightly shift of diffraction angle when compared with pure ceria. This result was due to strong metal-support interaction between platinum and ceria solid solution, causing conversion of Ce⁴⁺ to larger Ce³⁺. The distortions inside ceria lattice structure generated strain into the oxide lattice and facilitated the formation of oxygen vacancies which help to increase water gas shift performance. The H₂-Temperature Programmed Reduction indicated that the reduction peak of surface oxygen of 1%Pt1%Bi/CeO₂ shifts to lower temperature than that of 2%Pt/CeO₂ causing the enhancement of the water gas shift activity of this catalyst. Pt played an important role in catalyzing the surface reduction of ceria and addition of Bi alter the reduction temperature of surface ceria resulting in the improvement of the water gas shift activity of Pt catalyst.

Keywords: bismuth, platinum, water gas shift, ceria

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Authors: Victor R. Thulari, John Akach, Haleden Chiririwa, Aoyi Ochieng

Abstract:

Solar-light activated titanium dioxide photocatalysts were prepared by hydrolysis of titanium (IV) isopropoxide with thiourea, followed by calcinations at 450 °C. The experiments demonstrated that methyl orange in aqueous solutions were successfully degraded under solar light using doped TiO₂. The photocatalytic oxidation of a mono azo methyl-orange dye has been investigated in multi ion doped TiO₂ and solar light. Solutions were irradiated by solar-light until high removal was achieved. It was found that there was no degradation of methyl orange in the dark and in the absence of TiO₂. Varieties of laboratory prepared TiO₂ catalysts both un-doped and doped using titanium (IV) isopropoxide and thiourea as a dopant were tested in order to compare their photoreactivity. As a result, it was found that the efficiency of the process strongly depends on the working conditions. The highest degradation rate of methyl orange was obtained at optimum dosage using commercially produced TiO₂. Our work focused on laboratory synthesized catalyst and the maximum methyl orange removal was achieved at 81% with catalyst loading of 0.04 g/L, initial pH of 3 and methyl orange concentration of 0.005 g/L using multi-ion doped catalyst. The kinetics of photocatalytic methyl orange dye stuff degradation was found to follow a pseudo-first-order rate law. The presence of the multi-ion dopant (thiourea) enhanced the photoefficiency of the titanium dioxide catalyst.

Keywords: degradation, kinetics, methyl orange, photocatalysis

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Authors: Farrukh Jamil, Ala'a H. Al-Muhtaseb, Lamya Al-Haj, Mohab A. Al-Hinai

Abstract:

Date pits are major agricultural waste produced in Oman. Current work was conducted to produce jet fuel and green diesel from hydrodeoxygenation of Date pits oil in the presence of Pd/C catalyst. The hydrodeoxygenation of Date pits oil occurred to be highly efficient at following mild operating conditions such as conditions temperature 300°C pressure 10bar with continuous stirring at 500rpm. Detailed product characterization revealed that large fraction of paraffinic hydrocarbons was found which accounts up to 91.1 % which attributed due to efficient hydrodeoxygenation. Based on the type of components in product oil, it was calculated that the maximum fraction of hydrocarbons formed lies within the range of green diesel 72.0 % then jet fuel 30.4% by using Pd/C catalysts. The densities of product oil were 0.88 kg/m³, the viscosity of products calculated was 3.49 mm²/s. Calorific values for products obtained were 44.11 MJ/kg when Pd/C catalyst was used for hydrodeoxygenation. Based on products analysis it can conclude that Date pits oil could successfully utilize for synthesizing green diesel and jet fuel fraction.

Keywords: biomass, jet fuel, green diesel, catalyst

Procedia PDF Downloads 258