Rodriguez Herrero Yanet, Ullah Aman
Department of Agricultural, Food and Nutritional Science, 4-10 Agriculture/Forestry Centre, University of Alberta, Edmonton, Alberta, Canada T6G 2P5.
ACS Appl Mater Interfaces. 2023 Mar 22;15(11):14399-14414. doi: 10.1021/acsami.3c00183. Epub 2023 Feb 21.
The abundance of CO from the cement industry, power generation, petroleum production, and combustion of biomass makes it a readily available feedstock to produce chemicals and materials, although it has yet to achieve optimal development. Even though syngas (CO + H) hydrogenation to methanol is an established industrial process, when the same catalytic system based on Cu/ZnO/AlO is employed with CO, the water formed as a byproduct reduces the activity, stability, and selectivity of the process. Here, we explored the potential of phenyl polyhedral oligomeric silsesquioxane (POSS) as a hydrophobic support of Cu/ZnO for direct CO hydrogenation to methanol. Mild calcination of the copper-zinc-impregnated POSS material affords the formation of CuZn-POSS nanoparticles with Cu and ZnO homogeneously dispersed with an average particle size of 7 and 15 nm supported on O-POSS and D-POSS, respectively. The composite supported on D-POSS was able to reach a 3.8% yield of methanol with a 4.4% of CO conversion and with selectivity as high as 87.5% within 18 h. The structural investigation of the catalytic system reveals that CuO/ZnO are electron withdrawers in the presence of the siloxane cage of POSS. The catalytic system metal-POSS is stable and recyclable under H reduction and CO/H conditions. We tested the use of microbatch reactors in heterogeneous reactions as a rapid and effective tool for catalyst screening. The increased number of phenyls in the structure of POSS results in an increased hydrophobic character that plays a decisive role in the methanol formation after comparison with CuO/ZnO supported on reduced graphene oxide with 0% selectivity to methanol under the study conditions. The materials were characterized using scanning electron microscopy, transmission electron microscopy, attenuated total reflection Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, powder X-ray diffraction, Fourier transform infrared analysis, Brunauer-Emmett-Teller specific surface area analysis, contact angle, and thermogravimetry. The gaseous products were characterized by gas chromatography coupled with thermal conductivity detectors and flame ionization detectors.
水泥行业、发电、石油生产以及生物质燃烧所产生的大量一氧化碳，使其成为生产化学品和材料的现成原料，尽管其尚未实现最优发展。尽管合成气（CO + H）加氢制甲醇是一个成熟的工业过程，但当使用基于Cu/ZnO/Al₂O₃的相同催化体系处理CO时，作为副产物形成的水会降低该过程的活性、稳定性和选择性。在此，我们探索了苯基多面体低聚倍半硅氧烷（POSS）作为Cu/ZnO疏水载体用于直接CO加氢制甲醇的潜力。对浸渍了铜锌的POSS材料进行温和煅烧，可形成CuZn-POSS纳米颗粒，其中Cu和ZnO分别均匀分散在O-POSS和D-POSS上，平均粒径分别为7 nm和15 nm。负载在D-POSS上的复合材料在18小时内能够达到3.8%的甲醇产率、4.4%的CO转化率以及高达87.5%的选择性。对催化体系的结构研究表明，在POSS的硅氧烷笼存在的情况下，CuO/ZnO是吸电子体。催化体系金属-POSS在H₂还原和CO/H₂条件下是稳定且可循环使用的。我们测试了在多相反应中使用微型间歇反应器作为催化剂筛选的快速有效工具。与在研究条件下对甲醇选择性为0%的负载在还原氧化石墨烯上的CuO/ZnO相比，POSS结构中苯基数量的增加导致疏水性增强，这在甲醇形成过程中起决定性作用。使用扫描电子显微镜、透射电子显微镜、衰减全反射傅里叶变换红外光谱、X射线光电子能谱、粉末X射线衍射、傅里叶变换红外分析、布鲁诺尔-埃米特-泰勒比表面积分析、接触角和热重分析对材料进行了表征。气态产物通过气相色谱与热导检测器和火焰离子化检测器联用进行表征。
