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Hydrodeoxygenation of guaiacol as a model compound of bio-oil in methanol over mesoporous noble metal catalysts
Applied Catalysis A: General ( IF 4.7 ) Pub Date : 2018-01-09 , DOI: 10.1016/j.apcata.2018.01.008
E.A. Roldugina , E.R. Naranov , A.L. Maximov , E.A. Karakhanov

The liquid phase hydrodeoxygenation (HDO) of guaiacol (GUA), a model compound of bio-oil, was studied on bimetallic (PtPd) and monometallic (Ru) catalysts supported on mesoporous aluminosilicate of Al-HMS(X) type with different Si/Al (X) ratios and on mesoporous zirconia modified with silica (m-ZrO2-SiO2) in the presence of methanol as a solvent. The catalysts were characterized by NH3-TPD, TEM, XPS, 27Al and 29Si solid-state NMR and N2 adsorption–desorption methods. The influence of сatalyst loading, temperature, solvent/guaiacol ratio and contact time on the catalytic performance was investigated. It was established that, decreasing the Si/Al ratio and, correspondingly, increasing the acidity of the catalysts based on Al-HMS led to increasing conversion of guaiacol. Phenol, catechol, and their methylated derivatives were the main products of guaiacol HDO reaction in methanol at low catalyst loading (guaiacol/metal ratio, 800). It was found that the fraction of completely hydrodeoxygenated products (cyclohexane and methylcyclohexane) greatly increased as the catalyst loading grew (guaiacol/metal ratio, 160). Conversion of guaiacol on PtPd/m-ZrO2-SiO2 catalyst was higher than that on PtPd/Al-HMS(10), in accordance with the larger number of acid sites on the catalyst surface; however, the undesirable heavy fraction of methylated by-products was also higher. Ru-based catalysts exhibited the highest catalytic activity and showed unusually high selectivity toward fully hydrodeoxygenated products (cyclohexane, methylcyclohexane) in the HDO of guaiacol in the presence of methanol. Guaiacol can be efficiently converted into alkanes, with quantitative conversion and selectivity to cyclohexanes of 78% over Ru/Al-HMS(10) catalyst under relatively mild conditions (200 °C, 5 MPa H2). Methylation under the influence of methanol, deoxygenation on acid sites and aromatic ring hydrogenation on metal sites proceeded in a parallel way according to the suggested reaction pathways.



中文翻译:

介孔贵金属催化剂对愈创木酚作为甲醇中生物油的模型化合物进行加氢脱氧

在具有不同Si /的Al-HMS(X)型介孔铝硅酸盐负载的双金属(PtPd)和单金属(Ru)催化剂上研究了生物油的模型化合物guaiacol(GUA)的液相加氢脱氧(HDO) Al(X)比率和在以甲醇为溶剂的情况下用二氧化硅(m -ZrO 2 -SiO 2)改性的介孔氧化锆。通过NH 3 -TPD,TEM,XPS,27 Al和29 Si固态NMR和N 2对催化剂进行了表征。吸附-解吸方法。研究了催化剂用量,温度,溶剂/愈创木酚比和接触时间对催化剂性能的影响。已经确定,降低Si / Al比并相应地提高基于Al-HMS的催化剂的酸度导致愈创木酚的转化率提高。苯酚,儿茶酚及其甲基化衍生物是在低催化剂负载量(愈创木酚/金属比为800)下,愈创木酚HDO在甲醇中反应的主要产物。发现完全加氢脱氧的产物(环己烷和甲基环己烷)的分数随着催化剂载量的增加而大大增加(愈创木酚/金属比为160)。愈创木酚在PtPd / m -ZrO 2 -SiO 2上的转化催化剂比PtPd / Al-HMS(10)上的要高,这是因为催化剂表面上的酸点数量更多。但是,甲基化副产物的不希望的重质分数也更高。钌基催化剂在甲醇存在下,在愈创木酚的HDO中对完全加氢脱氧的产物(环己烷,甲基环己烷)表现出最高的催化活性和极高的选择性。愈创木酚可以在相对温和的条件下(200°C,5 MPa H 2)有效转化为烷烃,在Ru / Al-HMS(10)催化剂上定量转化和对环己烷的选择性为78%)。根据所建议的反应途径,在甲醇的影响下进行甲基化,酸位上的脱氧和金属位点上的芳环氢化以并行方式进行。

更新日期:2018-01-09
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