The Study Of Design And Fabrication Of Sulfided Mo-based Catalyst For Higher Alcohols Synthesis Via Syngas

Higher alcohol,a good gasoline additive,but currently syngas directly convert into higher alcohol is still challenging because of its lower catalytic efficiency.The thesis improves the performance of catalyst higher alcohol synthesis from syngas by modulating the metal elements in the catalyst.A KNiMoS catalyst with Zn-modified MgAl oxide as the carrier is synthesized by surfactant-assistance hydrothermal method.The introduction of Zn reduces the amount of strong acid in the catalyst,and also weakens the interaction between the carrier and the active component to adjust the reducibility of the catalyst,the degree of sulfidation and the distribution and stacking degree of MoS₂.K,NiMoS/Zn_0.35Mg_0.35Al_0.3 exhibits suitable acidity,high reducibility and sulfidity,and also contains a high proportion of double-layer MoS₂(43%) and highly synergistic NiS_x and KNiMoS phases.Thus,the total alcohol selectivity(56.5%)is achieved,in which the selectivity of C₂₊alcohol is82.2%.This study provides an efficient method that can simultaneously adjust the acidity of the catalyst and the interaction between the carrier and the active component,thereby improving the performance of the catalyst to directly synthesize low-alcohol via synthesis gas.The thesis also uses the co-precipitation and impregnation method,using Zn Al mixed oxide as a carrier to prepare a highly dispersed KNiMo-based catalyst.A multi-layered K-MoS₂ catalyst was designed,with well-contacted MoS₂ and KNiMoS,respectively.This structure is conducive to enhanced chain growth and C₂₊alcohol production through CH_x?insertion and CO insertion.By adjusting the K/Mo ratio,or obtaining catalysts with different MoS₂ and KNiMoS phase compositions,the formation of hydrocarbons and CO₂ can be effectively suppressed.The results show that`0.6KNiMoS/ZnAl has a suitable MoS₂ phase compared to KNiMoS,and also has more double-layer MoS₂(33.7%)and high synergy between MoS₂ phase and KNiMoS,which promotes chain growth and non-dissociated CO molecules incertion to acheive a high total alcohol selectivity(69.8%)and a high C₂₊space-time yield(78.6 mg/g_cat/h).