The present study reports the influence of the crystal phase, facets, and active sites of zirconium oxide (ZrO₂) on the conversion of bio-aldehydes to their corresponding alcohols in isopropanol under mild reaction conditions. Various ZrO₂-based catalysts, having different compositions of monoclinic and tetragonal crystal phases, are successfully prepared in the presence of a base via a solvothermal process. From the detailed characterization through XRD, TEM, CO₂-TPD, XPS, AES, BET and poisoning studies, M-ZrO₂-U-N, synthesized using zirconium oxynitrate and urea as a precursor and precipitant, respectively, in water, possesses a 100% monoclinic crystal phase with a maximum amount of exposed (−111) facets and surface oxygen concentration along with the highest number of basic sites. The catalytic study on the transformation of furfural (FFA) into furfuryl alcohol (FOH) reveals that M-ZrO₂-U-N exhibits the best efficiency with a nearly quantitative yield of FOH. On the other hand, T-ZrO₂-U-N, synthesized using zirconium oxynitrate and urea as a precursor and precipitant, respectively, in methanol, is found to have a 94.4% tetragonal phase and a 2.2-fold lower number of basic sites in comparison with M-ZrO₂-U-N. The catalytic result with T-ZrO₂-U-N displays the lowest activity in terms of the FOH yield (8.1%). According to the comparative and systematic catalytic studies with the various ZrO₂ catalysts having different amounts of tetragonal and monoclinic phases, the ZrO₂ catalyst having a more monoclinic phase with more exposed (−111) facets, basic sites, surface oxygen species and surface area is found to be crucial for the FFA conversion to FOH with high selectivity. M-ZrO₂-U-N is found to be stable and recyclable and also shows excellent activity towards the transformation of other bio-aldehydes and ketones into their corresponding alcohols.

中文翻译：

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解开氧化锆裸露晶面中的活性位点以进行生物醛的选择性加氢

本研究报告了在温和的反应条件下，氧化锆（ZrO ₂）的晶相，晶面和活性位点对生物醛向异丙醇转化为相应的醇的影响。具有单斜晶和四方晶相组成不同的各种基于ZrO ₂的催化剂，在碱的存在下通过溶剂热法成功地制备。通过XRD，TEM，CO ₂ -TPD，XPS，AES，BET和中毒研究的详细表征，M-ZrO ₂-UN分别使用硝酸氧锆和尿素作为前体和沉淀剂在水中合成，具有100％单斜晶相，具有最大的露面（-111）面和表面氧浓度以及最多的碱性位点。糠醛（FFA）转化为糠醇（FOH）的催化研究表明，M-ZrO ₂ -UN表现出最好的效率，几乎可以定量获得FOH。另一方面，与硝酸氧锆和尿素分别作为前体和沉淀剂在甲醇中合成的T-ZrO ₂ -UN相比，具有94.4％的四方相和低2.2倍的碱性位点与M-ZrO ₂ -UN T-ZrO ₂的催化效果-UN的FOH产率最低（8.1％）。根据与各种的ZrO比较和系统的催化研究_2层的催化剂具有不同量的四方晶和单斜相的，所述的ZrO ₂具有多个暴露（-111）面，碱性部位，表面氧和表面积更斜相催化剂发现对于以高选择性将FFA转化为FOH至关重要。发现M-ZrO ₂ -UN是稳定的和可回收的，并且对于其他生物醛和酮向其相应的醇的转化也显示出优异的活性。