碳材料以其低成本、良好的化学稳定性和热稳定性等优异特性被广泛应用于各种催化反应中。本研究利用来源广泛的天然脱脂棉为原材料, 通过原位气相掺杂的方法制备了N掺杂、B掺杂、BN共掺杂的生物质碳材料, 并将其应用在丙烷直接脱氢制丙烯反应中。研究发现, 与未掺杂的生物质碳相比, 杂原子掺杂的生物质碳均表现出更高的丙烷转化率和丙烯选择性, 而且N、B单独掺杂的生物质碳材料催化性能优于BN共掺杂的生物质碳材料, 其中N掺杂的生物质碳具有最优催化性能: 在600 ℃反应温度下, 丙烷转化率达到17.6%, 总烯烃收率达14.8%, 且经过12 h的脱氢反应后, 催化剂性能无明显的衰减。通过对这些碳材料的化学结构和催化性能的对比分析, 发现N掺杂和B掺杂使得碳材料表面的大量C-O基团转变为具有丙烷脱氢活性的C=O基团, 抑制反应过程中的C-C键断裂, 从而提高目标产物丙烯的选择性。生物质碳材料成本低廉且来源广泛, 以其作为催化剂可以极大地推动丙烷脱氢工业的发展。

Carbon materials have been widely used in various catalytic reactions due to their excellent properties, such as low cost and good chemical/ thermal stability. In this study, nitrogen-doped, boron-doped, and boron-nitrogen co-doped biochars were prepared by in-situ gas-phase doping strategy using natural absorbent cotton as the raw materials. In the reaction of direct dehydrogenation of propane to propylene, the heteroatom-doped biochar showed higher propane conversion and propylene selectivity than the undoped biochar. It was also found that the catalytic performance of nitrogen and boron independently doped biochar was better than that of boron and nitrogen co-doped biochar. The nitrogen-doped biochar exhibited the best catalytic performance of which, at the reaction temperature of 600 ℃, the propane conversion reached 17.6%, and the olefins yield was 14.8%. After dehydrogenation reaction for 12 h, the catalyst’s performance exhibited no apparent declination. The characterization results revealed that nitrogen doping and boron doping in biochars could transform many C-O groups on the surface of biochar into C=O groups at an advantage of propane dehydrogenation activity, which inhibits the C-C bond breaking in the reaction process and improves the selectivity of propylene. Furthermore, duo to biochars rich in resources and low cost, they would promote the industrialization of direct dehydrogenation of propane.