In this work, yttrium containing dealuminated Beta zeolites (Y/deAlBeta) were synthesized and characterized by various spectroscopic techniques to improve understanding of ethanol upgrading over these materials. Characterization results indicate yttrium atoms partially condense with framework silanol nests formed during dealumination of parent Al-Beta supports. Active sites for conversion of ethanol and acetaldehyde to butadiene were quantified on a series of Y/deAlBeta catalysts (0.1–10 wt% yttrium) via chemisorption and transmission Fourier transformed infrared (FTIR) spectroscopy measurements by first measuring the integrated molar extinction coefficient (IMEC) for pyridine bound to Lewis acidic yttrium sites. titrations with pyridine demonstrate that the number of sites quantified by chemisorption IR is quantitatively similar to the number of sites that catalyze butadiene formation, which varies (from 0.05 to 0.35) across the series of catalysts. pyridine titrations impact butadiene site time yields (STY), but not crotonaldehyde STY, indicating that a distribution of yttrium sites is present, and that discrete yttrium site types participate in distinct steps in the pathway from ethanol to butadiene. Apparent kinetic parameters including activation energies and reaction orders were measured, these suggest differences in reactant (or reactant-derived intermediate) surface coverages result in higher STYs (per mol Y or per Lewis acidic Y site) for samples with low Y loadings relative to those with higher Y loadings. Isotopic labeling experiments evince the existence of other kinetically relevant steps in addition to the crotonaldehyde transformation to crotyl alcohol. Together, these findings provide further guidance into the heterogeneities in site structures in yttrium-containing zeolites and their relevance for the various steps in the pathway from ethanol to C products useful for production of sustainable aviation fuel and renewable butadiene.

中文翻译：

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乙醇和乙醛转化为丁二烯过程中含钇脱铝β沸石活性位点的定量

在这项工作中，合成了含钇脱铝 Beta 沸石 (Y/deAlBeta)，并通过各种光谱技术进行表征，以提高对这些材料的乙醇升级的理解。表征结果表明，钇原子与母体 Al-Beta 载体脱铝过程中形成的骨架硅烷醇巢部分缩合。通过化学吸附和透射傅里叶变换红外 (FTIR) 光谱测量，首先测量积分摩尔消光系数 (IMEC)，对一系列 Y/deAlBeta 催化剂（0.1-10 wt% 钇）上乙醇和乙醛转化为丁二烯的活性位点进行定量）对于与路易斯酸性钇位点结合的吡啶。用吡啶滴定表明，通过化学吸附红外定量的位点数量在数量上与催化丁二烯形成的位点数量相似，该数量在一系列催化剂中变化（从0.05到0.35）。吡啶滴定影响丁二烯位点时间产率 (STY)，但不影响巴豆醛 STY，这表明存在钇位点分布，并且离散的钇位点类型参与从乙醇到丁二烯途径中的不同步骤。测量了包括活化能和反应级数在内的表观动力学参数，这些表明反应物（或反应物衍生的中间体）表面覆盖率的差异导致低 Y 负载量的样品相对于那些样品具有更高的 STY（每摩尔 Y 或每路易斯酸性 Y 位点）具有更高的 Y 载荷。同位素标记实验表明，除了巴豆醛转化为巴豆醇之外，还存在其他动力学相关步骤。总之，这些发现为了解含钇沸石位点结构的异质性及其与从乙醇到可用于生产可持续航空燃料和可再生丁二烯的碳产品的途径中各个步骤的相关性提供了进一步的指导。