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首页> 外文期刊>RSC Advances >Assembly line synthesis of isoprene from formaldehyde and isobutene over SiO2-supported MoP catalysts with active deposited carbon
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Assembly line synthesis of isoprene from formaldehyde and isobutene over SiO2-supported MoP catalysts with active deposited carbon

机译：活性沉积碳在SiO 2 负载的MoP催化剂上由甲醛和异丁烯合成流水线

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Isoprene is a very important monomer for synthetic rubber. Its synthesis in the presence of MoP catalysts via the vapour phase reaction of isobutene with formaldehyde has been studied. The catalysis by various catalysts was characterized by TG analysis, the low-temperature adsorption of nitrogen, XRD, element analysis, TPD, the FT-IR of adsorbed pyridine, XPS and MAS NMR. A chemical process was proposed and confirmed. Isoprene was synthesized in an “assembly line” process through different active sites at the surface of the MoP catalysts, where the active sites were derived from P and Mo species and deposited carbonaceous species. In the induction period, carbon species are preferentially deposited on P species, leading to a decrease in the active Mo and P species (active sites 1), accompanied with a burst in active carbonaceous species (active sites 2). This soundly describes the burst in catalyst capacity in the induction period, which then decreases over time on stream at the expense of the active carbonaceous species. Accordingly, through the prior formulation of sites 1 with sites 2 in a catalyst, the time-consuming induction period can be nearly eliminated. We also observed that a good ratio of these two active sites can efficiently retard the catalyst deactivation. This study clarifies the roles of acid sites and active species in MoP catalysts in the synthesis of isoprene and shows that their optimal ratio can help reduce the length of the induction period and extend the lifetime of the catalysts.
机译：异戊二烯是合成橡胶非常重要的单体。已经研究了在MoP催化剂存在下通过异丁烯与甲醛的气相反应合成的方法。通过TG分析，氮的低温吸附，XRD，元素分析，TPD，吡啶的FT-IR，XPS和MAS NMR表征了各种催化剂的催化作用。提出并确认了化学过程。异戊二烯通过“组装线”过程通过MoP催化剂表面的不同活性位点合成，其中活性位点来自P和Mo物种以及沉积的碳质物种。在诱导期，碳物质优先沉积在P物质上，导致活性Mo和P物质（活性位点1）减少，同时伴随着活性碳质物质（活性位点2）的爆发。这很好地描述了诱导期间催化剂容量的爆发，然后在生产中随着时间的流逝而减少，以活性碳质物质为代价。因此，通过预先在催化剂中制备具有位点2的位点1，可以几乎消除耗时的诱导期。我们还观察到这两个活性位点的良好比例可以有效地阻止催化剂的失活。这项研究阐明了MoP催化剂中异戊二烯的酸位和活性物质的作用，并表明它们的最佳比例可以帮助缩短诱导期的长度并延长催化剂的寿命。

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