Research On Catalytic Conversion Of Biomass

Biomass refers to all livings which can breed organic substances,among of them,the representative of biomass consist of agriculture,forestry residues,waste and grasses,etc.The source of Biomass energy is from the sun,wherein the non-food raw materials include cellulose,hemicellulose and lignin.Cellulose and hemicellulose can be used to produce sugar-based monomers,while lignin is mostly burned to provide heat and energy.The conversion of biomass into abundant and inexpensive ones could be widely used for bio-fuels,bio-based chemicals,biological materials,food,etc.The glucose and xylose are the monomers of cellulose and hemicellulose monomers,and always subjected to dehydration reaction.Benzene ring substances are usually selected as model compound of lignin to carry on further study.There are still many aspects of urgent expansion:a)the catalytic oxidation of lignocellulose process from the micro-macro perspective using nanocrystalline samples;b)looking for new catalysts to improve xylose dehydration performance in aqueous systems;c)With increased pollution problem,photocatalytic degradation colored waste has raised great interest.Based on the contents of the above points,the paper was divided into catalytic conversion of organic corn cob into organic acid using nanocrystalline species;xylose dehydration reaction into furfural in high temperature liquid water using zirconium phosphate;nitro-phenol hydrogenation raction using Ni-based catalysts and photocatalytic degradation of Rhodamine B using titanium dioxide-zirconium phosphate catalysts.Precipitation and hydrothermal methods are used to synthesis nano-CeO2,Al2O3,TiO2,ZrO2,both of them are used in the catalytic oxidation of corn cob in high temperature liquid water solution.Firstly,the hydrolysis process of cellulose and hemicellulose will occur in the high temperature liquid water to form the corresponding monomers glucose and xylose.Secondly,with the existence of oxygen,the sugar-based monomer will be transformed into organic acids.Therefore,glucose and xylose were also conducted in the oxidation reaction.The xylose is the main monomer of hemicellulose,and liquid acid,solid acid,transition metal oxides,carbonaceous catalyst were all used in the dehydration reaction of xylose.High temperature and a mixture solvent(water/toluene)or an organic solvent phase(dimethyl sulfoxide-DMSO)were both necessary in the dehydration reaction.The use of toluene and DMSO does not meet the green concept in industrial production.So,in this paper water was used as a reaction medium phase,the catalysts are involving H-ZSM-5 series,HPW(phosphotungstic acid)/C,HPW/SiO2,hydroxyapatite and zirconium phosphate series.Wherein hexadecyl trimethoxysilane was used to modify H-ZSM-5 to improve its hydrophobic properties;while HPW/C and HPW/SiO2 series use the matrix to enfold phosphotungstic acid to-preserve the activity of acid centers,and the corresponding easy separation will exist because of solid matrix;both of hydroxyapatite and xylose are belonging to the body of biomass,the use of "similar compatibility" principle could examine its xylose dehydration performance;mesoporous zirconium phosphate used improved hydrothermal method could preserve acidity and improved surface area,the existence of mesoporous also can improve the dehydration performance of xylose.In the agricultural and industrial wastewater,nitrophenol is a common organic pollutants,which its toxicity has great threat to the ecosystem.In this paper,the strong metal support interaction between the framework titanium of the titanium silicalite and metal Ni may exist.And the supported nickel catalyst was tested for the hydrogenation of p-nitrophenol,the conversion of nitrophenol could reach 25%.The interaction between nickel and titanium skeleton were characterized and the hydrogenation performance associated with the reaction was also discovered.In addition,the photochemical degradation of organic wastewater is currently an important issue.Based on the above results,the mesoporous zirconium phosphate shows better catalytic performance on xylose dehydration.The layered zirconium phosphate was synthesized by HF method,organic amine was intercalated in its interlayer and further TiO2 was introduced to improve the material's light,especially visible light absorption properties.Rhodamine B was selected to investigate the degradation properties of material which does reflect better photocatalytic degradation performance.To optimize the characterization results,a suitable Ti content is necessary which the smaller TiO2 particles(1-3 nm)could disperse on the zirconium phosphate substrate uniformly.The synergy effect between the layered zirconium phosphate combination of organic molecules and fine titanium oxide particles was important for better photodegradation performance.