Bifunctional base catalyst for vacuum residue cracking gasification

•Solid base cracking gasification process was used to processing vacuum residue.•A bifunctional base catalyst with both cracking and gasification activity was synthesized.•The self-made solid base catalysts have the desired moderate catalytic activity and stability.•The catalyst could be regenerated and produced H2-rich syngas via the coke gasification.

The residues cracking gasification was performed in a dual fluidized bed reactor by using calcium aluminate as the bifunctional catalyst, which was prepared by the solid phase method. Besides, carbon black assisted could contribute to improve the specific surface area of the catalyst. The performances of the reaction temperature and hydrothermal treatment catalysts on the products distribution for vacuum residue cracking were studied. It was found that solid base catalyst could promote to produce the products of light oils and light olefins, and co-producing the H2-rich syngas. The results showed that the C2 + C3 olefinicity of higher than 58.0%, heavy oil conversion of above 92.0%, and carbon deposited of ca. 4.2 wt% were achieved by cracking over two self-made solid base catalysts at 650 °C with a catalyst-to-oil ratio 7.0. Moreover, the catalyst with higher specific surface area displayed a better cracking performance than the one with lower specific surface area. Hydrothermal treatment base catalysts indeed decreased its activity, and thus led to higher liquid yield and lower gas yield. The carbon deposited on the catalyst was well gasified at 800 °C in steam-5.0 vol% oxygen. The H2 content and the H2/CO ratio were reached about 58.0 vol% and 4.5, respectively, with the CH4 content < 0.5 vol%. Besides, in comparison with an industry solid base catalyst, the coke gasification rate was obviously accelerated over two self-made solid base catalysts. Furthermore, the cracking performance of the solid base catalysts could reach basically stable via a few cracking gasification cycles.

Graphical abstractProducts composition of vacuum residue cracking gasification.Vacuum residue cracking gasification was intended to convert the residual oils into the products of light oils and light olefins, and the H2-rich syngas by using calcium aluminate as the bifunctional catalyst. The H2-rich syngas could be used to produce hydrogen to meet the need for hydrogenating low-grade oil feedstock and converting the cracked liquid.Figure optionsDownload full-size imageDownload as PowerPoint slide