Kulyk Kostiantyn, Palianytsia Borys, Alexander John D, Azizova Liana, Borysenko Mykola, Kartel Mykola, Larsson Mats, Kulik Tetiana
Stockholm University, AlbaNova University Center, Department of Physics, SE-106 91, Stockholm, Sweden.
Chuiko Institute of Surface Chemistry, National Academy of Sciences of Ukraine, 17 General Naumov Street, 03164, Kyiv, Ukraine.
Chemphyschem. 2017 Jul 19;18(14):1943-1955. doi: 10.1002/cphc.201601370. Epub 2017 May 10.
Valeric acid is an important renewable platform chemical that can be produced efficiently from lignocellulosic biomass. Upgrading of valeric acid by catalytic pyrolysis has the potential to produce value added biofuels and chemicals on an industrial scale. Understanding the different mechanisms involved in the thermal transformations of valeric acid on the surface of nanometer-sized oxides is important for the development of efficient heterogeneously catalyzed pyrolytic conversion techniques. In this work, the thermal decomposition of valeric acid on the surface of nanoscale SiO , γ-Al O , CeO /SiO , Al O /SiO and TiO /SiO has been investigated by temperature-programmed desorption mass spectrometry (TPD MS). Fourier transform infrared spectroscopy (FTIR) has also been used to investigate the structure of valeric acid complexes on the oxide surfaces. Two main products of pyrolytic conversion were observed to be formed depending on the nano-catalyst used-dibutylketone and propylketene. Mechanisms of ketene and ketone formation from chemisorbed fragments of valeric acid are proposed and the kinetic parameters of the corresponding reactions were calculated. It was found that the activation energy of ketenization decreases in the order SiO >γ-Al O >TiO /SiO >Al O /SiO , and the activation energy of ketonization decreases in the order γ-Al O >CeO /SiO . Nano-oxide CeO /SiO was found to selectively catalyze the ketonization reaction.
戊酸是一种重要的可再生平台化学品，可从木质纤维素生物质中高效生产。通过催化热解升级戊酸有潜力在工业规模上生产增值生物燃料和化学品。了解戊酸在纳米级氧化物表面热转化过程中涉及的不同机制，对于开发高效的非均相催化热解转化技术至关重要。在这项工作中，采用程序升温脱附质谱法（TPD MS）研究了戊酸在纳米级SiO₂、γ-Al₂O₃、CeO₂/SiO₂、Al₂O₃/SiO₂和TiO₂/SiO₂表面的热分解。傅里叶变换红外光谱（FTIR）也被用于研究戊酸在氧化物表面的络合物结构。根据所使用的纳米催化剂不同，观察到热解转化的两种主要产物——二丁基酮和丙基乙烯酮的形成。提出了由戊酸化学吸附片段形成乙烯酮和酮的机制，并计算了相应反应动力学参数。结果发现，乙烯酮化的活化能按SiO₂>γ-Al₂O₃>TiO₂/SiO₂>Al₂O₃/SiO₂的顺序降低，酮化的活化能按γ-Al₂O₃>CeO₂/SiO₂的顺序降低。发现纳米氧化物CeO₂/SiO₂选择性催化酮化反应。
