Silica support modifications to enhance Pd-catalyzed deoxygenation of stearic acid
Silica support modifications to enhance Pd-catalyzed deoxygenation of stearic acid
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DOI：
10.1016/j.apcatb.2016.03.041
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发表时间：
2016-09
影响因子：
22.1
通讯作者：
Nicolás A. Grosso‐Giordano;Todd R. Eaton;Zhenyu Bo;Sara Yacob;Chieh‐Chao Yang;Justin M. Notestein
中科院分区：
文献类型：
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作者：
Nicolás A. Grosso‐Giordano;Todd R. Eaton;Zhenyu Bo;Sara Yacob;Chieh‐Chao Yang;Justin M. Notestein
脂肪酸的催化脱氧最近作为用于生产具有比生物柴油更优越的上级性质的烃燃料的生物质原料脱氧的低氢方法而受到显著关注。不幸的是，这是一个具有挑战性的反应，以推动高产量。在典型的催化剂中，据报道，Pd/C通常具有最好的性能，而大多数氧化物载体都较差，但非常具体的制备和预处理方案除外。在这里，我们研究了有机硅烷改性的二氧化硅作为Pd催化硬脂酸在300 °C下在惰性气氛下脱氧的载体的作用。比较氨基丙基硅烷改性，苯基硅烷改性，和未改性的二氧化硅载体与Pd通过几种方法纳入，它首先表明，在分散单独的变化不占脱氧产率的改善。用苯基硅烷封端硅烷醇本身在提高脱氧产率方面也是无效的。最有效的处理方法是先用苯基硅烷和氨丙基硅烷共沉积，再用Pd等湿浸渍，然后直接还原催化剂，十七烷产率> 85%，甚至超过Pd/C的产率。这些结果表明，基本的，芳香族丰富的表面是通过有机硅烷接枝，这些表面可以控制钯的颗粒大小和硬脂酸和产品的吸附。这项工作提高了我们对生物质原料脱氧催化剂载体效应的理解，并有助于设计利用改性无机载体的新催化剂。
The catalytic deoxygenation of fatty acids has recently received significant attention as a low-hydrogen approach to biomass feedstock deoxygenation for production of hydrocarbon fuels with superior properties to biodiesel. Unfortunately, it is a challenging reaction to push to high yields. Of typical catalysts, Pd/C is typically reported to give the best performance, while most oxide supports are inferior, with exceptions for very specific preparation and pre-treatment protocols. Here, we investigate the role of organosilane-modified silicas as supports for the Pd-catalyzed deoxygenation of stearic acid at 300 °C under inert atmosphere. Comparing aminopropylsilane-modified, phenylsilane-modified, and unmodified silica supports with Pd incorporated by several methods, it is first shown that changes in dispersion alone do not account for improvements in deoxygenation yields. Capping silanols with phenylsilane is also ineffective on its own in improving deoxygenation yields. The most effective treatment is shown to be a co-deposition of phenylsilane and aminopropylsilane before Pd incipient wetness impregnation, followed by direct reduction of the catalyst, which gives heptadecane yields >85%, exceeding even the productivity of Pd/C. These results demonstrate that basic, aromatic-rich surfaces are accessible through organosilane grafting and that these surfaces can control Pd particle sizes and the adsorption of stearic acid and products. This work improves our understanding of support effects for biomass feedstock deoxygenation catalysts and could help design new catalysts that take advantage of modified inorganic supports.