Characteristics of co-pyrolysis of coal and FCC slurry and the evolution behavior of the produced gases

The co-processing of coal and oil changes the processing modes of direct coal liquefaction and heavy oil hydrocracking,reducing the difficulty of coal liquefaction,opening up new ways of direct coal liquefaction and heavy oil upgrading.It also provides technical support to promote the efficient and clean conversion of coal and heavy oil,which ensures the national energy security.However,the co-processing of coal and oil is often carried out under the conditions of high pressure,catalysis and hydrogenation.It is difficult to directly obtain the matching characteristics of thermal cracking behavior of coal and oil during the reaction,and not conducive to distinguish the interaction between different components.The pyrolysis and co-pyrolysis characteristics of a low metamorphic coal and a fluid catalytic cracking slurry (FCC) at different blending ratios were studied via thermogravimetry coupled with mass spectrometry.The intrinsic thermal reactions between the co-processing of coal and FCC was investigated by comparing the experimental and theoretical values.The results showed that the initial,peak and final pyrolysis temperature of the FCC are much lower than that of the coal,and the volatile content is significantly higher than the coal sample.At the initial stage of the reaction (200-400 ℃),the co-pyrolysis curves of coal and FCC is obviously shifted to a lower temperature region,indicating that synergetic effect exists during the co-pyrolysis of the coal and the FCC.When the reaction temperature is higher than 400 ℃,most of the FCC has volatilized,there is no obvious synergetic effect.Combined with online mass spectrometry data,the peaks of CO2 and CO was found in the pyrolysis temperature region of the FCC,at which mainly the FCC pyrolysis.It could be deduced to the solvent effect or the active metal contained in the FCC,which catalyzed the breaking of ether bond,hydroxyl or oxygen-containing molecule in coal.No interaction was observed during the co-pyrolysis of the coal ash and the FCC,while synergetic effect was observed during the co-pyrolysis of the FCC and the demineralized coal at 200-400 ℃,which further verifies the above deduction.