CNTs Doped/promoted Ni-Mo-K Sulfide And Perovskite Catalyst For The Synthesis Of Higher Alcohols From Syngas

Higher alcohol synthesis from carbon based materials including coal or biomass via syngas has important strategic significance and potential applications prospect based on the potential use of higher alcohols as value-added chemical feedstock,alternative fuels and gasoline additives and the structural features of energy,'rich coal,poor oil and little gas',in our country.In this dissertation,a novel CNTs doped/promoted Ni-Mo-K sulfide catalyst and Cu-Fe perovskite catalyst are prepared.The catalysts are tested for higher alcohols synthesis from syngas.The relationship between structure and catalytic performance are studied by a series of characterizations.The main results are as follows:1.CNTs doped/promoted Ni-Mo-K sulfide catalystBy the optimization using designed experiments,the catalyst composition was determnined as Ni1Mo1K1-10%CNTs and the reaction conditions for the catalyst performance were as below:P = 5.0 MPa,T-320 ?,GHSV = 3000 mL/(g·h),and n(H2)/n(CO)= 1.The results indicated that the NiiMo1K1-10%CNTs catalyst displayed the highest CO conversion of 13.2%,and its selectivity to total alcohols and ethanol arrived 60.4%and 30.2%.Further study on the amplification experiment was carried out.The results showed that the Ni1Mo1K1-10%CNTs catalyst showed a better catalytic performance under the evaluating conditions of P = 6.0 MPa,T= 320 ?,GHSV = 3000 mL/(g h)and n(H2)/n(CO)= 1.The space-time yield of total alcohols and ethanol arrived 111.6 mg/(g·h)and 54.8 mg/(g·h).The physical properties of the catalysts:the specific surface area is more than 9 m2/g,the compressive strength is more than 95 N/cm,and the abrasion is less than 0.09%.The Ni1Mo1K1-10%CNTs catalyst also exhibited excellent stability.The CO conversion,ethanol selectivity,total alcohol selectivity did not show obvious drops for 300 h.The promotion effects of CNTs-on Ni-Mo-K sulfide catalyst can be essentially ascribed to the following two aspects:(1)CNTs can provide sp2-C surface active sites foradsorption and activation of H2,which are in favor of generating a surface microenvironment of high concentration of sp2-C-H on the functioning surface of the catalysts;(2)The molar fraction of the active species NiO(OH)and Mo4+/Mo5+increased significantly on the functioning surface of the catalysts.2.Perovskite catalystA kind of Cu-Fe catalyst was fabricated by using perovskite LaMn0.7Cu0.3O3-supported Fe2O3 as precursor followed by controlled reduction.The results showed that 5%Fe2O3/LaMn0.7Cu0.3O3-0.75CA(CA:citric acid)reduced 400? possessed the best catalytic performance under the evaluating conditions of P=3.0 MPa,T = 260 ?,GHSV = 3000 mL/(g·h)and n(H2)/n(CO)= 2.The catalyst displayed the highest CO conversion of 8.0%,and the selectivity to total alcohols and C2+-OH of 32.2%and 59.9%,respectively.This catalyst also exhibited excellent stability,sustaining higher catalyst performance for 300 h.Further,the study of A-site deficient perovskite catalysts on higher alcohol synthesis showed that A-site deficient of perovskite can obviously improve performance,giving 11.7%CO conversion,34.4%total alcohol selectivity,and 71.2%C2+-OH selectivity.The preliminery characterizations revealed that the A-site deficient perovskite benefited the formation of Cu-Fe alloys during the reduction pretreatment and thus the catalyst derived presented improved performance.