Catalytic performances of HZSM-5, NaY and MCM-41 in two-stage catalytic pyrolysis of pinewood

Experiments were carried out in an atmospheric two-stage fixed bed reactor to investigate the catalytic cracking of pinewood pyrolysis vapour over three single catalysts, HZSM-5, NaY and MCM-41. The pinewood was pyrolyzed in the first stage reactor at a heating rate of 10 degrees C min(-1) from room temperature to 700 degrees C, and the resultant vapour was cracked through the second reactor at a temperature of 500, 600 or 700 degrees C with and without catalyst. Both the gases and liquid compounds were thoroughly determined. It was found that all three catalysts had significant catalytic effects on the vapour cracking especially in the range of 500-600 degrees C. However, three catalysts showed dissimilarity to each other with respect to the distributions of products. Among three catalysts, HZSM-5 displayed the highest selectivity for the formation of olefins and light aromatics, with the least deposit of coke, though NaY showed the strongest capability of deoxygenation. The HZSM-5 cracking at 600 degrees C was preferred to balance the yield and quality of bio-products. MCM-41 behaved as a worse catalyst in the deoxygenation, and its resultant liquid product contained more heavy aromatics.