A Study On The Aromatics Separation From Shenhua Coal Hydroliquefaction Light Oil And Rehydrogenation Behavior Of Hydroliquefaction Products

Compared to petroleum, coal hydroliquefaction oil as the rough product of coal hydroliquefaction contains considerable aromatics.It is of high consuming of hydrogen when hydrogenate aromatics deeply in order to produce fuel oil with regulated aromatics contents. Aromatics as the important basic chemical material play a key role in economic development. Separation of aromatics from coal hydroliquefaction oil can not only control the aromatics content in regulated contents, but also make a new stock method to produce aromatics. Coal hydroliquefaction residue as the by-product accounts for much and has low values. It's significant to study hydrogenation of coal hydroliquefaction residue for improving the yield of coal hydroliquefaction oil and the economic value of coal hydroliquefaction process.Coal hydroliquefaction light oil obtained from Shenhua pilot plant was analysed and rectified into distillation A and distillation B. Distillation B was further rectified and simulated by ASPEN PLUS. And distillation B was extracted by solvent to enrich aromatics. Hydrogenation of phenanthrene was studied and catalyst was synthesized. A light oil fraction from lignite moderate hydroliquefaction was analyzed by extraction and GC-MS and its hydrogenation was examined in micro-autoclave. One type of low temperature coal tar was analyzed by column chromatogram and GC-MS and its hydrogenation was studied in autoclave. Hydrogenation of coal hydroliquefaction residue obtained from Shenhua pilot plant was studied and its kinetics was proposed.The results of Shenhua coal liquid light oil separation show that cycloalkane enrich in distillation A and aromatics enrich in distillation B. Tetralin can be purified to 70wt% by the primary distillation of distillation B with the optimal reflux 4 and the yield of tetralin in raffinate oil during the tetralin producing stage is 46.78%. The purification of tetralin can improve to 85% after the second distillation of the product obtained in transition stage and the yield of tetralin is up to 67.53%. The simulation result by ASPEN PLUS is coincident with the experiment. The total content of aromatics in extract oil is 87.70% which increases by 18.95% compared to the content of aromatics in distillation B and the aromatic yield is 39.75% when distillation B extracts by sulfolane with solvent to oil 3, thinner 0.5% and extract temperature 40℃. The total content of aromatics in extract oil is 86.90% and the aromatics yield increases from 15.94% to 42.65% when the ratio of furfural to sulfolane is 2:1, the solvent to oil ratio is 1 and the extract temperature is 40℃.The results of penanthrene hydrogenation exhibit a high hydroconversion of 61.82% under 430℃,8MPa using FW-20. With a weak acidity, FW-20 can not make ring opening and cracking of phenanthrene while using molecular sieves as carrier, synthesized catalyst can do it.Analysis of lignite coal liquid light oil shows this light oil includes a large number of acidic compound up to 23.46% and neutral compound up to 75.86%. Acidic compound is rich in phenol and its derivative and neutral compound is rich in aromatics. Although the chemical process of light oil hydrogenation by using FW-20 is complicated, it could ascribe by hydrogenation and dealkylation. The variation content of mono-aromatics is 11.65% by the hydrogenation of multi-aromatics under 430℃. The variation content of low boiling phenolic compound reaches to 8.69% by dealkylation of high boiling phenolic compound under 430℃.Low temperature coal tar enriches in aromatics and polar compound with a total content up to 90.71%. Di-aromatics accounts for 88.95% in the total aromatics. Polar compound contains a considerable amount of oxygen-containing compounds which include large number of phenolic compound. Aromatics content increases and polar compound content decreases with the temperature and the initial hydrogen pressure increase using FW-20. Aromatics content increases to the maximum of 68.88% and the polar compound decreases to the minimum of 16.68% under 430℃,8Mpa. Using Ni-W/USY instead of FW-20 as the catalyst can improve the reaction of opening ring and cracking and dealkylation.The result of hydrogenation of coal residue indicates prolonging reaction time is beneficial to improving oil and gas yield under the moderate hydrogenation condition. Oil and gas yield increases from 14.14% to 40.86% under 470℃,30min. Considering about the nonuniform of tetrahydrofuran insoluble part, a 4-lumped kinetic model is proposed. It shows that the apparent activation energy of asphaltene to form oil and gas is 36.79 kJ·mol-1, which is low.