快速热解炭负载Cu-Zn对碱木质素热裂解生成单酚类化合物的催化性能

以具备丰富中孔和大孔结构的快速热解炭(FPC)为载体,采用共浸渍法制备了不同Cu/Zn摩尔比的CuxZny/FPC负载型催化剂.采用X射线衍射仪(XRD)、高分辨场发射扫描电子显微镜(FE-SEM)及电子能谱仪(EDX)对催化剂进行了表征,采用热重分析仪(TG)和热解气质联用仪(Py-GC/MS)评价了催化剂对碱木质素热裂解生成单酚类化合物的催化性能.结果表明,催化剂活性组分Cu O和Zn O晶相结构均一,很好地嵌入到FPC中孔和大孔结构中,未发生聚集状态或生成Cu Zn合金;随着Cu或Zn金属负载量的增大,相应的Cu或Zn金属氧化物衍射峰强度逐渐增强,平均晶粒尺寸逐渐增大.热重分析结果表明,催化剂降低了碱木质素热裂解残炭率和反应活化能,提高了热裂解反应效率.热解气质联用分析表明,CuxZny/FPC催化剂大幅度简化了碱木质素热裂解单酚类化合物种类(从23种减少到了10种),Cu0.67Zn0.33/FPC对单酚类化合物表现出最大的选择性(52.99%),与Cu/FPC相比选择性增加49.7%.

Catalytic Properties of Fast Pyrolysis Char Loaded with Cu-Zn on Alkali Lignin Pyrolysis for Monophenols

The fast pyrolysis char( FPC) , which was a kind of mesoporous and macroporous carbon materials, was loaded with different molar ratios of Cu and Zn using the co-impregnation method to prepare the catalysts of Cux Zny/FPC. The catalysts were characterized by X-ray diffraction ( XRD ) , field-emission scanning electron microscope(FE-SEM) and energy dispersive X-ray spectroscopy(EDX). The catalytic properties on generating monophenols from alkali lignin pyrolysis were determined by thermogravimetric analyzer( TG) and pyrolysis-gas chromatography/mass spectrometry( Py-GC/MS) . The results showed that the active components of CuO and ZnO were homogeneously embedded into the mesoporous and macroporous structure of FPC without the occurrence of aggregation or copper zinc alloy. With the metal loading increased, the diffraction peak intensity of CuO and ZnO was enhanced and average crystal sizes of CuO and ZnO became larger gradually. TG analysis showed that the catalysts significantly improved the reaction efficiency by reducing the activation energy while inhibited the formation of char residues. The monophenols obtained from the catalytic pyrolysis of alkali lignin were simplified from 23 kinds to 10 kinds. The catalyst of Cu0. 67 Zn0. 33/FPC had the highest selectivity of monophenols up to 52 . 99%, and the selectivity increased by 49 . 7% compared with the catalyst of Cu/FPC.