Effects of K2CO3 on pyrolysis characteristics of Xinjiang cotton stalk

Abstract

The horizontal fixed bed pyrolysis method was used in this study to examine the reaction parameters of K in-situ catalytic pyrolysis of the cotton stalk at 600 °C. The pyrolysis conversion mechanism of cotton stalk under the influence of K was investigated in conjunction with gas chromatography analysis, FT-IR analysis, and GC-MS analysis. According to the findings, the gas production of a mixture of 1 g cotton stalks grew from 215 mL (0.0 %- K2CO3) to 275 mL (7.5% -K2CO3), but it was inhibited to 263 mL when K2CO3 addition was at 10.0%. According to the results of the characterization, K2CO3 might accelerate the breakdown of oxygen-containing rings in cellulose and hemicellulose, encourage the conversion of furan structure into ketones, and prevent the transformation of furan into long-chain alkanes. The addition of K2CO3 introduces more K into the cotton stalk. Under the influence of K, long-chain alkanes, phenols, and esters will be further cracked and polymerized to create more stable aromatic hydrocarbons. According to quantum chemical calculations, xylose's oxygen-containing ring opened first without the presence of K, then H transfer, dehydrogenation, dehydration, and cyclization to generate the cyclopentanone structure. The oxygen-containing groups in the xylose side chain preferentially bind to K in the presence of K, and the bond length between the O and C rings of the side chain is lengthened, while without K, the C–O bond length of the preferred ring opening is shortened.