以木屑为碳源、尿素为氮源、KOH为活化剂，制备了系列氮掺杂生物质碳CH4-CO2重整催化剂。采用比表面孔结构分析仪、电镜、红外和热重等表征手段对新鲜和使用后的催化剂样品结构和特性进行了分析，考察了催化剂孔结构、N含量、N种类和碱性位等对重整催化性能的影响。研究发现，N掺杂可以显著提升生物质碳材料N及碱性位含量，从而为重整反应提供更多的活性位点；其中，后处理掺N制备的生物质碳材料（BC-750/3.5-N）氮质量分数高达26.35%。而原位N掺杂可以进一步促进造孔作用，使样品NBC-750/3.5获得大量的微孔或窄微孔，同时提高其比表面积和孔体积（1 981.53 m2/g和1.08 mL/g），从而有利于重整反应气体的吸附和活化。研究还发现，原位N掺杂制备的NBC-750/3.5催化剂样品中吡啶N和吡咯N占比较高，分别为31%和50%。其中，掺杂的吡咯N有利于CO2吸附，吡啶N有利于气体分子活化，因此通过原位掺杂制备的碳材料催化剂催化性能较好。催化重整50 h后，CH4和CO2转化率仍稳定在45%和62%左右。同时发现，重整反应后吡啶N和吡咯N占比降低，石墨N占比增加。因此，通过调控催化剂的制备方法和N杂原子掺杂方式，可以更准确地调控含N基团的生成类型和含量，从而通过调控制得高性能非金属碳基非再生型重整催化材料。

Using wood chips as carbon source,urea as nitrogen source and KOH as activator,a series of nitrogen-doped biomass carbon CH4-CO2 reforming catalysts were prepared. The structure and properties of fresh and spent catalyst samples were analyzed by surface pore structure analyzer,electron microscopy,infrared,and thermogravimetric characterization. The effects of pore structure,nitrogen content,nitrogen species (pyridine nitrogen,pyrrolic nitrogen and graphitic nitrogen) and basic sites on the reforming performance were investigated. The study found that nitrogen doping can significantly increase the nitrogen and basic site content of biomass carbon materials,providing more active sites for the reforming reaction. The nitrogen content of the biomass char material (BC-750/3.5-N) prepared by post-processing nitrogen was as high as 26.35%. The in-situ nitrogen doping can promote the activated pore formation of KOH,so that the sample NBC-750/3.5 can obtain a large number of micropores or narrow micropores. The specific surface area and pore volume are 1 981.53 m2/g and 1.08 mL/g,respectively,which are conducive to the adsorption of raw gas. Meanwhile,the characterization results show that the proportion of pyridinic nitrogen and pyrrolic nitrogen in the NBC-750/3.5 catalyst samples prepared by in-situ nitrogen doping is relatively high,which are 31% and 50%,respectively. The pyrrolic nitrogen is favorable for CO2 adsorption,and the pyridine nitrogen is favorable for molecular activation,so the prepared carbon material catalyst exhibits excellent catalytic performance. After 10 hours of catalytic reforming,the conversions of CH4 and CO2 remain stable at about 45% and 62%. It is also found that after the reforming reaction,the proportion of pyridine nitrogen and pyrrolic nitrogen decrease,and the proportion of graphitic nitrogen increases. By changing the preparation method of biochar and nitrogen doped method,the existence form of nitrogen containing groups can be more accurately regulated,so that high activity and stability of carbon-based non-regenerated catalytic materials can be obtained through controlled preparation. 

0 引言

1 试验

   1.1 试剂

   1.2 催化剂样品制备

   1.3 样品活性测试

   1.4 样品表征

2 结果与讨论

   2.1 不同催化剂的孔结构特性分析

   2.2 样品的表面形态结构

   2.3 催化剂元素分析

   2.4 样品红外表征

   2.5 样品的XPS表征分析

   2.6 CO2-TPD和TG表征分析

   2.7 不同催化剂性能评价

3 结论