Mineral evolution and catalytic mechanism in catalytic gasification of petroleum coke with coal/biomass ash

Abstract

This work investigated the formation and transformation of minerals in the catalytic gasification of petroleum coke with different characteristics of ash, and further revealed the catalytic mechanism. An isothermal gasification experiment under H2O atmosphere was conducted on a self-designed thermogravimetric analyzer. The results show that biomass ash has better catalytic gasification effect due to its higher active mineral content. Simultaneously, coal/biomass ash can effectively change the petroleum coke structure during gasification, and promote the decomposition of C = C, C–C, thiophene and sulfoxide in petroleum coke. The good correlation (correlation coefficient is 0.96) between the structural parameters (ID1/IG, ID3/IG and IG/IALL) indicates that only the mineral elements with catalytic activity in the ash can effectively change the structure of petroleum coke. Sulfur content in petroleum coke at high H2O concentration does not combine with minerals to form sulfide or sulfate, which leads to the deactivation of minerals. The results also show that the catalytic gasification effect of ash is affected by two factors: melting characteristics and the content of catalytic active minerals. At low addition ratio (≤20 %), the catalytic effect of ash mainly depends on the content of active minerals in ash. At high addition rate (≥20 %), the fluidity advantage brought by ash melting begins to play an important role.