Ga-MCM-41 synthesis and catalytic activity in the liquid-phase isomerisation of α-pinene
Ga-MCM-41 synthesis and catalytic activity in the liquid-phase isomerisation of α-pinene
复制标题
DOI：
10.1016/j.micromeso.2007.02.022
复制
发表时间：
2007-06-20
影响因子：
5.2
通讯作者：
Angel Romero, Antonio
中科院分区：
文献类型：
--
作者：
Luque, Rafael;Manuel Campelo, Juan;Angel Romero, Antonio
报道了以硝酸镓和正硅酸乙酯（TEOS）分别为镓源和硅源合成Ga-MCM-41材料的方法。合成了硅镓比为40、30、20和10的样品，并以吡啶（PY）和2，6-二甲基吡啶（DMPY）为探针分子，采用XRD、N2吸附、SEM、DRIFT、表面酸性等表征手段，以及吡啶在气相中吸附的DRIFT，对样品进行了液相α-蒎烯异构化反应的测试。根据文献，异构化通过两个平行和竞争的途径进行，一个产生单环产物，另一个产生多环产物，这取决于催化剂的酸强度。主要产物为莰烯和柠檬烯。在弱（刘易斯酸中心）中形成了莰烯和多环产物，而强（布朗斯台德）酸中心导致了柠檬烯和单环衍生物。在温和的反应条件下（353 K），材料表现出一个有趣的催化活性的转化率和选择性，以异戊烯和柠檬烯。在反应1小时后和进一步反应后达到最高转化率值（约60-70%）。反应时间似乎没有显著增加材料活性。(c)2007年爱思唯尔公司All rights reserved.
A procedure to synthesize Ga-MCM-41 materials, using gallium nitrate and tetraethyl orthosilicate (TEOS) as gallium and silica sources, respectively, is reported. Samples were synthesized with a silica/gallium ratio of 40, 30, 20 and 10 and subsequently characterised by XRD, N-2 adsorption, SEM, DRIFT measurements and acid properties as surface acidity using pyridine (PY) and 2,6-dimethylpyridine (DMPY) as probe molecules, as well as, DRIFTs of absorbed pyridine in gas phase.Materials were tested in the liquid-phase-alpha-pinene isomerisation reaction. According to the literature, the isomerisation proceeds via two parallel and competing pathways, one yielding monocyclic products and the other yielding polycyclic products depending on the catalysts acid strength. Camphene and limonene were obtained as major products. Camphene and polycyclic products are formed in weak (Lewis acid sites) whereas stronger (Bronsted) acid sites resulted in limonene and monocyclic derivatives. Materials exhibited an interesting catalytic activity in terms of conversion and selectivity to camphene and limonene under mild reaction conditions (353 K). The highest conversion values (around 60-70%) were achieved after 1 h of reaction and further. reaction times did not seem to increase, significantly, the materials activity. (c) 2007 Elsevier Inc. All rights reserved.