Catalytic Conversion Of Biomass To Fuel And Value-added Chemicals Under Hydrogen-free/Low Hydrogen Pressure Condition

In the current society,the structure of energy is focused on fossil fuels,which not only increase the CO2 content in the atmosphere and cause pollutions,but also make people finally face the problem of running out of energy resources.Lipid and lignin are two important reproducible biomass and are expected to be the substitute for fossil fuels,providing fuels and chemicals.However,usually high H₂ pressure is demanded during their hydrogenation and deoxygenation processes,which result in the increasing cost and security problems.Thus there is necessity for the design and development of synthesis routes and effective and stable catalysts for the conversion of liqid and lignin to fuels and value-added chemical under no-hydrogen or low-hydrogen-pressure conditions.In this work,we have:1)developed effective and highly stable catalysts for the deoxygenation of lipid without hydrogen;2)designed strategy for the process from lipid to bio-based lubricant base oil and developed corresponding catalysts;3)developed catalysts withstanding harsh hydrothermal conditions for the process of selectively hydrogenation and deoxygenation of lignin phenol derivatives under hydrothermal conditions with low hydrogen pressure.During investigation,we uncovered the structure-efficiency relationship between catalysts and reactions via the detailed research of catalyst structure and in situ spectroscopic characterizations.?1?Highly effective and stable Pt/HAP-IE catalyst was synthesized by ion-exchange,which achieved 50 wt%conversion of stearic acid at⁶.0 g?g?h^-1 and 89%yield of heptadecane.Such catalyst is also adapted to the deoxygenation of lipid with various triglyceride fatty acid ester structures and can be directly used in the conversion of unprocessed catering waste oil.A variety of characterizations such as CO₂-TPD?NH₃-TPD and FTIR illustrate that the exchange site between Pt precursor and HAP is the surface OH^-during ion-exchange.This catalyst possesses uniform metal particle with the average particle size of only 0.7 nm.In addition,it exhibited high stability,with high reactivity maintained after 8 cycles and the average particle size became 1.6nm.The adsorption of propionic acid model compounds and in situ diffuse reflections show that carboxylic acids adsorb in the form of bidentate chelation on the HAP surface.This kind of special adsorption form activates carboxylate group and make C-C break easier.?2?A new synthesis route from stearic acid to value-added lubricating base oil,composed of three steps:stearic acid deoxygenation to internal olefin under non-hydrogen condition,internal olefin polymerization and poly internal olefin hydrogenation.Firstly,Pt₂Sn₂/SiO₂ was obtained for stearic acid deoxygenation under no-hydrogen conditions and it could convert stearic acid to internal olefin mixtures at320°C and achieved 97%conversion and 73%olefin yield.The combined XRD,TEM and XPS characterizations identified that the active site is PtSn alloy.The modified SnO_x on the surface of alloy was also found.Adsorption of propanoic acid model compounds and in situ diffuse reflections reveal that carboxylic acid adsorbs on SnO_x in the form of acyl and C-C break occurs and produces CO and olefin.The KMnO4oxidation method identified that the produced internal olefin was mainly 7-heptadecene,8-heptadecene and 2-7-heptadecene.Subsequently,internal olefin was polymerized and hydrogenated using AlCl3 as the polymerization catalyst and produced bio-based lubricant base oil.After performance test,the pour point is-24°C and viscosity index is 186,which is comparable with commercial lubricant oil.?3?Ru/LaCO₃OH catalyst withstanding harsh hydrothermal conditions was developed for the system of lignin phenol oil conversion to aromatics under hydrothermal and low-hydrogen-pressure conditions,which we have already reported.This catalyst coud convert guaiacol to phenol under 240°C,2 bar H₂ hydrothermal conditions,with the initial conversion rate of 3.24 g?g^-1?h^-1,98.5%guaiacl conversion and 91%phenol yield.After 4 cycles,the catalyst still remained high reactivity and no change in morphology was observed.We have done detailed research in the catalyst synthesis and found that the precursor RuCl₃?3H₂O reacted with LaCO₃OH during impregnation and formed RuLa compound which is difficult to be reduced.Under the hydrothermal condition with low H2 pressure,the surface of RuLa species decomposed,generated LaCO₃OH and Ru nanoparticles,and formed the structure of partially wrapped in the support.This structure could stabilize Ru nanoparticles,thus the catalyst could endure harsh hydrothermal conditions.