In-Situ Catalytic Pyrolysis of Xylan and Dealkaline Lignin over SAPO-11

Silicoaluminophosphate molecular sieve, SAPO-11, was applied for the first time to the catalytic pyrolysis of xylan and dealkaline lignin. The isothermal fast catalytic pyrolysis of xylan and dealkaline lignin over different amounts of SAPO-11 and their product analysis were performed concurrently using a pyrolyzer GC/MS. Large amounts of oxygenated pyrolyzates produced from the non-catalytic pyrolysis of xylan at 500 °C were converted to furans, light hydrocarbons, and aromatic hydrocarbons using SAPO-11. When the catalyst to sample ratio was increased from 1:1 to 5:1 and 10:1, the selectivity toward aromatic hydrocarbons was increased dramatically. Phenolic compounds, such as guaiacols and vanillin, were the main products of the non-catalytic pyrolysis of dealkaline lignin. These phenolic compounds were upgraded efficiently into aromatics by the catalytic pyrolysis of dealkaline lignin over SAPO-11. By increasing the catalyst to sample ratio from 1:1 to 10:1, much larger amounts of aromatic hydrocarbons were obtained due to the increased catalyst acid sites. A phenolic pool mechanism was suggested as the major reaction pathway for the catalytic pyrolysis of dealkaline lignin over SAPO-11.