Hydrogenolysis Conversion Of Alkali Cellulose To C2~C3Polyols

Cellulose in one of the most abundant biomass resources in nature, and itscatalytic conversion to energy chemicals or fine chemicals is also one of importantways to the utilization of biomass resources. Hence, focusing on the influence ofalkaline pretreatment to cellulose conversion into C2~C3polyols, the hydrogenolysisreaction system was investigation.The alkali cellulose preparation conditions and influencing factors were firstlyinvestigated, including the alkali concentration, pretreatment time, the amount ofcellulose in processing and so on. TEM and XRD results showed that the cellulosedegree of crystallinity and degree of polymerization became reduced and theamorphous regions in cellulose surface were formed though the alkaline pretreatmentto increase the accessibility of cellulose; the alkali cellulose could absorbed the NaOHcrystals in its structure, the alkali absorption was increased with the raise of theconcentration of NaOH in alkaline pretreatment process. The results for catalytichydrogenation reaction of alkali cellulose showed the appropriate alkali pretreatmentcondition:4wt%NaOH solution at room temperature treating5wt%cellulose for2hours, under the optimized conditions, the catalytic hydrogenation reaction of alkalicellulose was investigated, in order to Ru/C as the catalyst, reaction was conducted at433K for5hours, with the conversion rate of59.23%, and the main products were1,2-propylene glycol and ethylene glycol, based on the product distributions underdifferent reaction conditions, the corresponding reaction mechanism was proposed.The ionic liquids stabilized metal nano-ruthenium particles were prepared bychemical reduction of the precursor RuCl3in the mixture of NaBH4aqueous solutionand ionic liquids which was used as a protective agent and dispersing agent. ThroughTEM, XRD, TGA, and FTIR characterization, the TEM results showed that the Runanoparticles were spherical in morphology, uniform particle size distribution, andless than5nm of average particle size; the XRD results showed that the Runanoparticles were the hexagonal close packing structure in this reduction system andno oxide was formed; the TGA results showed that because of the ionic liquids on thesurface of Ru nanoparticles, they had a good thermodynamic stability within a certain temperature range; the FTIR results showed that the ionic liquid coating on the metalin the form of physical adsorption to prevent oxidation and agglomeration of the Runanoparticles. Comprehensively, in the process of synthesis of Ru nanoparticles, theionic liquids in the form of physical adsorption rather than chemical action coating onthe metal surface play a role as dispersing agent and protective agent. The ionic liquid[Bmim] PF6and [Bmim] BF4stabilited Ru nanoparticles were obtained with smallerparticle size and good dispersion, and the ionic liquid [Bmim] Cl and [HO-emim] Clstabilited Ru nanoparticles also had a molecular diameter of less than5nm, but thedispersion was poor.The nano-ruthenium catalysts in alkali cellulose hydrogenolysis system for theoptimization of reaction conditions were investigated. Investigated factors includingreaction temperature, reaction time, amount of catalyst and so on. According to theanalysis of the previous characterization results and reaction products, the using ofRu/[Bmim]BF4catalyst revealed a good performance. The optimal reaction conditionsfor the hydrogenolysis reaction is operated at433K for5h, resulting a betterconversion and C2~C3polyol selectivity which in the case of the conversion rate of63.78%, glycerol,1,2-propylene glycol and ethylene glycol selectivity, respectively,18.37%,22.55%and17.99%respectively.