The Study Of Catalyst System And Technology For The Synthesis Of Alcohol-Base Liquid Fuel From Biomass Gasificationt

This paper was studied the preparation of catalysts and technology for conversion reforming of biomass gasification gas to low-carbon alcohol liquid fuel were investigated.By modifying the catalysts,the effective enrichment of HZ and CO in biomass gasification gas was achieved,the ratio of H2 to CO was increased,and the synthesis of low-carbon alcohol liquid fuel was also achieved under low temperature and low pressure.Firstly,using cordierite as carrier and vacuum impregnation method,a Ni-based polymetallic composite catalyst was prepared.Using simulated gas as model component of biomass gasification gas,the key technological factors affecting the catalytic activity in the process of H2 and CO enrichment were investigated in a fixed-bed reactor.The results showed that the content of H2 and CO increased by 192.3%and 220.4%respectively under the conditions of reaction temperature at 750 C and flow rate at 300 scem,using 3%Ni-1%Co-1%Rh/cordierite as catalyst.The catalytic activity of 3%Ni-1%Co/cordierite can be stabilized for about 100 hours,while that of 3%Ni-1%Co-1%Rh/cordierite is more than 150 hours.Secondly,after the experiment of increasing H2 and CO content,the above-mentioned catalytic cracking gas is used as a raw material gas,and the self-made HZSM-5 molecular sieve is used as a carrier,and the active metals component were supported by a vacuum impregnation method,and the fixed bed is used as a reactor,and the reforming process was carried out by introducing CH4.The reaction temperature of 700? was the best.Under the condition of gas flow rate of 300 scem,the conversion of CH4 was 68.4%,the conversion of CO2 was 58.1%on 8%Ni-5%Co/HZSM-5 zeolite catalyst,the content of C2H6 was inversely proportional to the content of H2 and the ratio of H2 to CO was 2.20.After continuing to load the Rh noble metal,the conversion of CH4 on the 8%Ni-5%Co-1%Rh/HZSM-5 zeolite catalyst is 70.3%,and the CO2 conversion rate is 55.3%and the H2/CO ratio is 2.47.The H2/CO ratios of the two catalysts meet the requirements for the direct synthesis of short-chain alcohol-based liquid fuels in the next step,and the non-precious metal-modified 8%Ni-5%Co/HZSM-5 catalysts can be regenerated by high-temperature calcination.After 2 regenerations,it still maintains good catalytic activity and stability.In addition,XRD,BET,NH3-TPD,H2-TPR,SEM,TEM and other characterization methods were used to study the changes of catalyst structure,characteristics and carbon deposition during the reforming process,and the reaction and carbon deposition during the reforming process were discussed.Finally,short-chain alcohol-based were synthesized on the basis of H2/CO ratio of 2.20 obtained by oriented reforming of catalytic cracking.The CuFeNi/ZrO2 catalyst carrier was prepared by coprecipitation method,and different content of alkali metal K was introduced into catalyst carrier by vacuum impregnation method.The increase of alkali metal K component could obviously enhance the desorption ability of CO on catalyst surface and enhance the conversion of CO in feed gas.At the same time,the selectivity of CxHy and CO2 will be reduced,and the selectivity of total alcohols of target produce be enhanced.With the increase of total alcohol selectivity,methanol selectivity has been greatly improved,the highest selectivity can reach 57.7%.The purpose of synthesizing low-carbon alcohols has been achieved.Reaction temperature has a significant effect on the activity of catalysts and the selectivity of main and by-products.Although the increase of reaction temperature can significantly enhance the conversion of CO,the selectivity of C,Hy and CO2 in products will also be obvious.The selectivity of total alcohols was significantly increased and decreased.Therefore,it was appropriate to consider the reaction temperature at 280? and the gas flow rate is 50 ml/min,The conversion of CO was 46.8%,the selectivity of total alcohols was 45.4%,the selectivity of CH3OH in total alcohols was 57.7%,the selectivity of C2H5OH was 37.3%,and the total selectivity of two short-chain alcohols was 95%.The introduction of precious metal Rh enhances the interaction between Ni crystal particles and cordierite catalyst,further increasing the dispersion of Ni crystal particles,and significantly improves the overall catalytic activity and carbon deposition resistance of the catalyst.In addition,the catalysts were characterized by XRD,BET,NH3-TPD,H2-TPR,SEM,TEM and TG-DTG.The structure,characteristics and carbon deposition of the catalysts were analyzed by the characterization results.The positive and negative chemical reactions and the mechanism of carbon deposition during the reaction were analyzed.The surface acidity of the catalysts was improved and the carbon deposition rate was reduced.The kinetics process of CH4 reforming reaction was simulated by using series dynamics model and MVK dynamics model.The reaction kinetics model was established,which provided theoretical support for the adjustment of process parameters such as catalyst particle size,reaction temperature and gas flow rate.