Balasubramanian V V, Devassay B M, Halligudi S B, Deepika R, Umbarakar S B, Vinu A
Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN-55455, USA.
Catalysis Division, CSIR-National Chemical Laboratory, Pune 411008, India.
J Nanosci Nanotechnol. 2018 Apr 1;18(4):2986-2992. doi: 10.1166/jnn.2018.14342.
We demonstrate a highly active and reusable heterogeneous catalyst system, tungstophosphoric acid (TPA) supported on zirconia (ZrO2), for the cyclohexylation of resorcinol by cyclohexanol to produce value added chemicals such as 2-cyclohexyl resorcinol, 4-cyclohexyl resorcinol and 3-Hydroxy cyclohexyl phenyl ether under liquid phase reaction condition. TPA/ZrO2 catalysts prepared with different TPA loadings (5-30 wt.%) by wet impregnation method and calcined in the temperature range of 650-850 °C were characterized by Nitrogen sorption analysis, XRD, FTIR, DTG and DTA, and 31P MAS NMR spectroscopy. Among the catalysts studied, 15 wt.%TPA/ZrO2 catalyst calcined at 750 °C gave the highest conversion of resorcinol (51.2%) with the selectivities for 3-Hydroxy cyclohexyl phenyl ether (53.9%) and 2-cyclohexyl resorcinol and 4-cyclohexyl resorcinol together (46.1%) under optimum reaction conditions. However, the selectivity of the products were controlled by varying the reaction conditions. At higher conversion of resorcinol (78.9%), only C-alkylated products were formed at 200 °C with 15 wt.%TPA/ZrO2 catalyst calcined at 750 °C. The combination of TPA and ZrO2 coupled with calcination temperature offered an excellent platform for the conversion of resorcinol into O- or C-alkylated products.
我们展示了一种高活性且可重复使用的多相催化剂体系，即负载在氧化锆（ZrO₂）上的钨磷酸（TPA），用于在液相反应条件下，通过环己醇将间苯二酚进行环己基化反应，以生产增值化学品，如2 - 环己基间苯二酚、4 - 环己基间苯二酚和3 - 羟基环己基苯基醚。通过湿浸渍法制备了不同TPA负载量（5 - 30 wt.%）并在650 - 850 °C温度范围内煅烧的TPA/ZrO₂催化剂，采用氮气吸附分析、XRD、FTIR、DTG和DTA以及³¹P MAS NMR光谱对其进行了表征。在所研究的催化剂中，在750 °C煅烧的15 wt.%TPA/ZrO₂催化剂在最佳反应条件下使间苯二酚的转化率最高（51.2%），对3 - 羟基环己基苯基醚的选择性为53.9%，对2 - 环己基间苯二酚和4 - 环己基间苯二酚的选择性总和为46.1%。然而，通过改变反应条件可以控制产物的选择性。在间苯二酚较高转化率（78.9%）时，在200 °C下使用在750 °C煅烧的15 wt.%TPA/ZrO₂催化剂仅形成C - 烷基化产物。TPA与ZrO₂的结合以及煅烧温度为将间苯二酚转化为O - 或C - 烷基化产物提供了一个极好的平台。
