摘要: The catalytic effects of different catalysts, i.e., 3% Ca, 5%Na-BL, and 3% Ca+5% Na-BL catalyst, on carbon conversion, gasification reaction rate constant, activation energy, and relative amount of harmful sulfur containing gases, were investigated by thermogravimetry in steam gasification under temperature 700℃ to 900℃ at ambient pressure for two Pakistani Lakhra (LKH) and Thar (THR) lignite chars. High carbon conversion can be obtained by direct gasification of both LKH and THR chars, but the gasification rate became much fast using BL catalyst. THR char with high ash content was easy to form some complex silicates during BL catalytic gasification, leading to a lower conversion than that of LKH char with low ash content. SO2 and H2S as sulfurcontaining gases produced by char and BL itself in steam gasification can be captured by the existence of Ca mixed with BL, which is more effective at temperatures less than 900℃. The shrinking core model (SCM) can be considered as a better choice to correlate the relations between conversion and time and to estimate the reaction rate constant (k) under different temperatures. The reaction activation energy (Ea) and preexponential factor (A) were predicted based on Arrhenius equation. The reaction activation energy of 44.7kJ/mol and 59.6kJ/mol for LKH chars with BL+Ca and BL catalysts were much lower than 114.6kJ/mol and 100.8kJ/mol for THR chars with the same catalysts, respectively. They were also lower than 161.2kJ/mol for LKH char and 124.8kJ/mol for THR char without catalyst.
摘要: Catalytic pyrolysis of Chinese Daqing atmospheric residue on a commercial fluid catalytic cracking (FCC) catalyst was investigated in a confined fluidized bed reactor. The results show that the commercial FCC catalyst has good capability of cracking atmospheric residue to light olefins. The analysis of gas samples shows that the content of total light olefins in cracked gas is above 80%. The analysis of liquid samples shows that the content of aromatics in liquid samples ranges from 60% to 80%, and it increases with the enhancement of reaction temperature. The yield of total light olefins shows a maximum with the increase of reaction temperature, the weight ratios of catalyst-to-oil and steam-to-oil, respectively. The optimal reaction temperature, the weight ratios of catalyst-to-oil and steam-to-oil are about 650℃, 15 and 0.75, respectively.
