Preparation And Properties Of Cellulose Hydrogenation Catalyst

Cellulose is one of the most abundant form biomass resources in the world, the transformation of cellulose to fuels and chemicals has triggered more and more intense world-wide research interest. Cellulose conversion via one-pot method in hot-compressed water to sorbitol, mannitol, ethylene glycol, propylene glycol and other polyols, which provide one of efficient and greener way for cellulose conversion.Sorbitol is an important platform chemical molecules, which was widely used as a sweetening agent, preparation of vitamin C, propylene glycol, synthetic resin, wetting agent and stabilizer products, etc.. Cellulose hydrolysis hydrogenation product complexity, leading to the yield of single target product is low. The question is how to reconcile the problem of cellulose hydrolysis reaction and catalytic hydrogenation reaction to obtain a high yield of sorbitol.In this thesis, a series of PtNi catalysts were prepared with various supports (MESHZSM-5, MESNaZSM-5, MESHMOR) and their catalytic properties were investigated for the hydrogenation of cellulose after addition compressed CO2. Compressed CO2 can reduce the crystallinity of cellulose and promote the hydrolysis of cellulose. To elucidate the roles of CO2 for the high selectivity to sorbitol, the hydrogenation of glucose, fructose, sorbitol, and mannitol, which are reaction intermediates of cellulose hydrolytic hydrogenation, were preformed with and without the presence of compressed CO2. Compressed CO2 not only inhibited glucose isomerization to fructose, but also inhibited sorbitol conversion to mannitol and small molecule alcohol.X-ray photoelectron spectroscopy indicated that Ni species interacted strongly with the lattice oxygen in carrier, which makes it difficult to be fully reduced with hydrogen. N2 adsorption isotherms confirmed that both of the micro- and meso- pores were present on carriers. There were no diffraction peaks of metal Pt on X-ray diffraction pattern so that no large Pt particles were generated on the catalyst. Each catalyst had only one peak on TPR profile, which indicated PtNi nanoparticles were uniformly distributed on carriers.