High catalytic activity and stability quasi homogeneous alkali metal promoted Ni/SiO_2 aerogel catalysts for catalytic cracking of n-decane

摘要

In this study, a series of M-Ni/SiO2 (M = Na, K) aerogel catalysts were synthesized and applied in n-decane cracking in supercritical conditions. Meanwhile the catalytic activity was investigated and compared with conventional wall-coated catalysts, in order to explore the feasibility of Ni/SiO2 aerogel as quasi homogeneous catalyst and find a new method to improve catalytic activity, stability and reduce the coking for hydrocarbons cracking reaction. N-2 adsorption-desorption, XRD, SEM-EDS, TEM, H-2-TPR and CO2-TPD were used to find the correlation among catalytic activity, stability and catalyst microstructure. The results revealed that the series M-Ni/SiO2 (M = Na, K) aerogel catalysts which are well dispersed in n-decane show better catalytic activity, stability and anti-coking ability compared with wall-coated Ni/SiO2 catalyst, moreover, the catalyst dosage is only a half of wall-coated catalyst. Furthermore, Na and K promoted Ni/SiO2 aerogel catalysts exhibit excellent stability within 50 min at 750 degrees C and 3.5 MPa. Characterization results indicated that higher surface area, larger pore size, smaller Ni particle sizes, higher Ni dispersion due to stronger active metal-support interaction and proper basicity can be responsible for good catalytic activity, better coke resistance and stability of M-Ni/SiO2 aerogel catalysts.