生物质组分快速热解联产生物质炭和碳纳米管的研究

Rapid Pyrolysis of Biomass Components to Produce Biochar and Carbon Nanotubes

关键词:  生物质  热解  生物质炭  化学气相沉积  碳纳米管

Key Words:biomass  pyrolysis  biomass carbon  chemical vapor deposition  carbon nanotubes

摘要:以纤维素、木聚糖和碱木质素为原料，通过快速热解的方法，使热解挥发性组分在泡沫镍催化下形成上层炭，同时固体产物形成残留固体炭（即下层残炭）。纤维素和木聚糖所得上层炭中含有大量的碳纳米管（CNTs），且掺杂有部分石墨片，而碱木质素则难以形成CNTs。其中，纤维素CNTs比木聚糖CNTs含有更多的石墨化碳，并且纤维素CNTs的石墨化程度、比表面积和产率均较高。纤维素残炭和木聚糖残炭则为致密块状结构，石墨化程度低；纤维素残炭的得率更高，因此纤维素整体的利用率比木聚糖高。结果表明，纤维素和木聚糖的热稳定性较低，热解过程可以产生大量的挥发性组分，且大多为小分子，为CNTs的形成提供了较充足的碳源，而碱木质素的热稳定性高，且热解气体产物少，不利于CNTs的形成。

Abstract:Cellulose， xylan and alkali lignin were used as raw materials to produce an upper carbon layer with nickel foam catalyst from the pyrolyzed volatile components and residual solid carbon （i.e.， lower residual carbon） via rapid pyrolysis. The upper carbon layer obtained from cellulose and xylan contained a large number of carbon nanotubes （CNTs） and was partially doped with graphite flakes， whereas alkali lignin was difficult to form CNTs. The cellulose CNTs contained more graphitized carbon than xylan CNTs， and the degree of graphitization， specific surface area and yield of cellulose CNTs were higher. Cellulose residual carbon and xylan residual carbon had a dense lumpy structure with a low degree of graphitization. The yield of cellulose residual carbon was higher， thus the overall utilization of cellulose was higher than that of xylan. The results showed that cellulose and xylan had lower thermal stability， and the pyrolysis process could produce a large number of volatile components， and most of them were small molecule， which provided a more sufficient carbon source for the formation of CNTs， while alkali lignin had a high thermal stability and fewer gaseous products of pyrolysis， which was not conducive to the formation of CNTs.