Utilization of bifunctional catalyst for upgrading petroleum residue via cracking and gasification: Effect of catalysts

Vacuum residue is stepwise and high-efficient converted by the base cracking and coke gasification process. Cracking effect of vacuum residue was carried out with different bifunctional catalysts in a fluidized bed reactor, respectively. Calcium aluminate catalyst specialized for cracking and gasification procedure is selected with the activities of cracking and gasification. In comparison with silica sand, calcium aluminate catalyst showed the higher vacuum residue cracking activity, and cracking activity gradually increased with increasing the Ca/Al ratios. The results indicated that C2-C4 olefinicity of above 60.4%, cracking-generated coke of about 5.0 wt%, and light oil yields is over 84.0 wt% at 650 degrees C with a catalyst-to-oil ratio of 7.0. Moreover, it was also found that calcium aluminate catalyst synthetized with the Ca/Al molar ratio of 12:7 and carbon black as pore-forming agent displayed a better cracking properties than that of the other catalysts. VR cracking properties over calcium aluminate catalysts was closely related to their basicity, as indicated by the Hammett indicators method. Cracking-generated coke on the base catalyst was well gasified with pure steam at 800 degrees C and produced the syngas with the total content of H-2 and CO2 up to 81.5 vol%, the coke conversion over the tested catalysts is of above 93.6% in 30 min. Also, the alternating base cracking and gasification operations were performed three times to verify the stability of the optimal calcium aluminate catalyst. The selected catalysts presented high hydrothermal stability and stable cracking activity, which could be potentially used for vacuum residue stepwise and high-efficient utilization via vacuum residue catalytic cracking and gasification regeneration process. (C) 2018 Energy Institute. Published by Elsevier Ltd. All rights reserved.