Catalytic Hydrocracking Of Shengli Lignite Over Fe-S

Hydrocracking is one of the most important reactions for direct coal liquefaction. Preparation of catalysts with high activity is the core technology in the hydrocracking process. Three solid acid catalysts(NSA, PCA/AC and TMSTFMS/AC) were prepared by impregnating the same volume of pentachloroantimony(PCA), trimethylsiyl trifluoromethanesulfonate(TMSTFMS), or isometric PCA and TMSTFMA into an activated carbon(AC). Through FTIR, SEM, EDS, BET, NH3-TPD and XRD analyses reveal the strong interactions among PCA, TMSTFMA and AC in the NSA, and NSA exhibits appreciably stronger acidity than the other two catalysts. Di(1-naphthyl) methane(DNM) was used as a coal-related model compound to evaluate their catalytic activity. The DNM hydrocracking reactions show that Car-Calk bond in DNM can be selectively cleaved over each catalyst to afford naphthalene and 1-methylnaphthalene under preesurized hydrogen at temperatures up to 300 oC, but as a new solid acid, NSA is significantly more active for DNM hydrocracking than the other two catalysts. The yield of naphthalene is appreciably higher tnan that of 1-methylnaphthalene over any catalysts and the difference in yield between the two products increased with raising the reaction temperature, indicating that the 1-methylnaphthalene demethylation proceeded and became significant at higher temperatures. DNM conversion, the product yields basically increased with the increases in the NSA feed, reaction time and initial hydrogen pressure.Shengli lignite(SL) and Shengli lignite extraction residue(SLER) were selected as the analysis samples in the catalytic hydrocracking reactions with Fe-S/ZSM-5 at 300 oC. The products were analyzed with GC/MS and were qualitative and quantitative analysis. Different solvents were selected as the reaction solvent(cyclohexane, toluene, methanol, ethanol, and isopropyl alcohol), compared the reactions products from catalytic hydrocracking(CH) and TD. The PESFs from the products of hydrocracking reactions from the coal samples can be classified as alkanes, alkenes, arenes, phenols, esters, ethers, and other species organic compounds, most of them were alkanes arenes and phenols, which were detected by GC/MS. The yields of arenes and phenols of products from CH were significant higher than that from TD under the Fe-S/ZSM-5, which clarified that Fe-S/ZSM-5 can promote the release of small organic molecules and special structure species in coal macromolecular structure. Moreover, the yields of reaction products(cyclohexane, methanol and ethanol as reaction solvents) were higher than that from reaction products toluene and isopropanol as reaction solvents). Non-polar solvents cyclohexane favor the presence of hydrogen radicals which beneficial the catalytic hydrocracking; The methanol and ethanol are involved in the alcoholysis which promoting fracture coal macromolecular structure, While the poor effect in isopropanol, because its larger molecules is not conducive to alcoholysis reaction process, steric effect is more obvious. The number of aromatic ring of arenes in products from SLER is less than 5, and phenols and naphthols are the main component of phenols in products from SLER. And mostly dominated aromatic alkyl substituents such as methyl naphthalene, anthracene and methyl methyl pyrene; alkanes content of more, and mainly for the C10-C27, and mainly were straight-chain alkanes, accounting for about one-third of two; in addition a large number of aromatic ether compounds detected in the product, and the CH were higher than TD, indicating that the catalyst added is in favor of the cleavage of carbon bonds and aromatic aryl ether between coal macromolecular structure and the dissolution of small molecules.