Preparation And Catalytic Properties Of Ni-W-P-B Amorphous Catalyst And MoS₂ Catalyst For P-cresol Hydrodeoxygenation

With the depletion of fossil fuels and in the process of using fossil fuels caused serious environmental problems, which has caused widely sought to explore sustainable and renewable alternative fuel. Bio-oil which obtained by high temperature cracking from lignocellulose is considered to be the ideal substitute,because it has no emissions in the process of burning sulphur oxides and other advantages. However, bio-oil due to its high oxygen content, leading to low calorific value, chemical instability, and not mix with other fossil fuels, these are not conducive to direct use of bio-oil as commonly fuel, so must be deoxidized refined.Catalytic hydrodeoxygenation（HDO） as a kind of very effective biological oil refining technology has caused wide attention.Generally, phenols HDO mechanism includes direct hydrogenolysis（DDO） route yielding aromatic products and hydrogenation-dehydration（HYD） route producing cycloalkanes. The DDO route requires a high reaction temperature, HYD route can significantly decrease the reaction temperature, the key is to prepare a HDO catalyst with high activity.Amorphous catalyst has some special properties such as microstructure of long-range disorder and short-range order,leading to its excellent activity and selectivity in the catalytic reactions.This study of first part focused on the preparation of Ni-W-P-B amorphous catalysts by chemical reduction methodand the effect of Ni/W molar ratio on their catalytic activities in the hydrodeoxygenation（HDO） of phenols in the bio-oil.As result,adding NH3·H₂O could generate a complex between Ni²⁺ and NH3·H₂O inhibited the reaction rate of Ni²⁺ with BH4-, leading to a high Ni0 content on the catalyst surface,wich is one of the important reasons for the catalyst showed highly active.The catalyst exhibited the highest HDO activity When Ni/W molar ratio is 1,the deoxygenation degree reached to 100% with aconversion of 100%at 498 K and 3 MPa.Also,Ni-W-P-B amorphous catalysts possessed a dehydro-genation activity at the same condition.In the second part of study,With commercial MoS₂ as raw materials, the exfoliated MoS₂ catalyst with a large specific surface area was prepared by adopting n-butyl lithium embedded into the MoS2 crystals. BET, XRD, SEM characterization results showed that the improved preparation method via adding cationic surfactant CTAB into the exfoliation process could reduce the height of the stack layers of MoS₂,whereas for the adding of anionic surfactant, the exfoliation effect could not be promoted. The main products for the hydrodeoxygenation（HDO） of p-cresol by MoS₂ catalyst were 4-methylcyclohexene, methylcyclohexane and toluene. The exfoliated MoS₂ catalyst had two catalysis activated sites which located at the “Edge” and the“Rim” of the layers of the crytals and 1the HDO reaction was much easier to occur at the "Edge". Adding Ni or Co into the exfoliation MoS₂ catalyst could improve the activity of HDO and the introduction of Ni could promote the toluene converting into methylcyclohexane, implying that the addition of Ni into the exfoliation MoS₂ is more beneficial to the improvement of the fuel oil quality origined from bio-oil raw material. However, the HDO reaction activity of the exfoliated MoS₂ was not yet high enough with the addition of Ni or Co into the catalyst,it may be ascribed to the limitation of the specific structureand the chemical activity of MoS₂.