{"title":"A Two-Step, Temperature-Staged Direct Coal Liquefaction Process ","authors":"Reyna Singh, David Lokhat, Milan Carsky ","volume":103,"journal":"International Journal of Chemical and Molecular Engineering","pagesStart":896,"pagesEnd":903,"ISSN":"1307-6892","URL":"https:\/\/publications.waset.org\/pdf\/10002510","abstract":"
The world crude oil demand is projected to rise to 108.5 million bbl\/d by the year 2035. With reserves estimated at 869 billion tonnes worldwide, coal remains an abundant resource. The aim of this work was to produce a high value hydrocarbon liquid product using a Direct Coal Liquefaction (DCL) process at, relatively mild operating conditions. Via hydrogenation, the temperature-staged approach was investigated in a dual reactor lab-scale pilot plant facility. The objectives included maximising thermal dissolution of the coal in the presence of tetralin as the hydrogen donor solvent in the first stage with 2:1 and 3:1 solvent: coal ratios. Subsequently, in the second stage, hydrogen saturation, in particular, hydrodesulphurization (HDS) performance was assessed. Two commercial hydrotreating catalysts were investigated viz. NickelMolybdenum (Ni-Mo) and Cobalt-Molybdenum (Co-Mo). GC-MS results identified 77 compounds and various functional groups present in the first and second stage liquid product. In the first stage 3:1 ratios and liquid product yields catalysed by magnetite were favoured. The second stage product distribution showed an increase in the BTX (Benzene, Toluene, Xylene) quality of the liquid product, branched chain alkanes and a reduction in the sulphur concentration. As an HDS performer and selectivity to the production of long and branched chain alkanes, Ni-Mo had an improved performance over Co-Mo. Co-Mo is selective to a higher concentration of cyclohexane. For 16 days on stream each, Ni-Mo had a higher activity than Co-Mo. The potential to cover the demand for low–sulphur, crude diesel and solvents from the production of high value hydrocarbon liquid in the said process, is thus demonstrated. <\/p>\r\n","references":"[1] R. Salmon, H.D. Cochran, L.E. McNeese, \u201cStatus of coal liquefaction in\r\nthe United States,\u201d Fossil Energy Office \u2013 United States Department of\r\nEnergy, pp. 195-205, 1979.\r\n[2] S. Vasireddy et al., \u201dClean liquid fuels from direct coal liquefaction\r\nchemistry, catalysis, technological status and challenges\u201d, Energy\r\nEnvironmental Science, vol. 4, pp. 311-345, 2011.\r\n[3] I. Mochida, O. Okuma, and S. Yoon, \u201cChemicals from Direct Coal\r\nLiquefaction,\u201d ACS Publications Special Issue: Chemicals from Coal,\r\nAlkynes, and Biofuels, vol. 114, pp. 1637\u20131672, 2014.\r\n[4] B.C. Gates, \u201cLiquefied Coal by Hydrogenation,\u201d Chemtech, pp. 97\u2013102,\r\n1979.\r\n[5] Y. Gota, K. Ishida, \u201cCoMo\/NiMo Catalyst Relay System for Clean\r\nDiesel Production,\u201d Petroleum Refining Research and Technology\r\nCenter, Japan, 2000.\r\n[6] J.J de Vlieger, \u201cAspects of the chemistry of hydrogen donor solvent coal\r\nliquefaction\u201d1988.\r\n[7] W.M. Reed at al., \u201cThe Response of High Temperature Catalytic\r\nTetralin-Hydrogen Reaction to Free Radical Addition,\u201d Auburn\r\nUniversity, Department of Chemical Engineering, pp. 83-91\r\n[8] C. Song, A.K. Saini, H.H. Schobert, \u201cEnhancing low-severity catalytic\r\nliquefaction of low-rank coal,\u201d Fuel Science Programme, USA, pp.\r\n1031-1038, 1987\r\n[9] A. W. Drews, \u201cManual on Hydrocarbon Analysis,\u201d 6th edition, 1998.\r\n[10] M. Klee, \u201cGC Solutions #20: Calibration Curves \u2013 Part 2, Internal\r\nStandard Approach,\u201d 2013.\r\n[11] Bureau Veritas - South African National Accreditation System\r\n(SANAS) Testing Laboratory, 2012\r\n[12] Sigma Aldrich, 2014 ","publisher":"World Academy of Science, Engineering and Technology","index":"Open Science Index 103, 2015"}