Investigation of the direct catalytic conversion of methanol and ethanol to propylene

在气候变化、乙醇价格下降、乙烯和丙烯需求和价格上升的背景下，开发新的可持续的、有目的的方法，将乙烯、（生物）乙醇和甲醇转化为“绿色”丙烯和其他烯烃，是本十年的一项主要任务。与布拉斯科在聚合物行业的“绿色”乙烯相比，生产丙烯的新方法以及PP、PEG等的后续产品引起了相当大的关注。从目前沸石上醇类催化直接转化和烃池转化的现状来看，出现了两个主要的经济问题：(i)对于不同的工艺条件和催化剂材料，哪种转化途径能促进甲醇或乙醇生成所需的产物丙烯？（ii）哪种催化剂性能促进了从甲醇、乙醇或两者混合物中选择性生产丙烯的预期转化路线？从更科学的角度来看，以下问题将得到更深入的研究：（iii）哪些催化表面反应步骤和哪些相互依赖的动力学是选择性丙烯形成所必需的？（iv）从热力学来看，哪些过程路线主要由焓驱动，哪些由熵驱动，哪些由孔隙几何形状和形态重新导向？工作计划分为沸石合成与表征、催化测试和机理评价实验。除了催化剂的固态表征（XRD， NMR， IR， SEM， EDX, ICP-OES， TPD）外，连续模式的催化测试将结合复杂的吸附动力学机理研究（例如Howarth动力学）和详细的烃产物网络（中间体）。作为一个专业，我们将通过d6 -乙醇和13c -甲醇的混合同位素置乱实验和GC/MS分析来研究静态反应链网络相互依赖的新机理结论。尽管目前的讨论，它应该揭示不同的直接和池形成路线丙烯的动态竞争，而不是完全排除某些路线。此外，实验将揭示高选择性的参数场对催化剂各自失活行为的影响。以知识为基础的转化路线控制将使设计适合工业的催化剂成为可能。就目前的价格发展而言，已经存在对MTP技术（甲醇制丙烯）的需求，并且在未来5-10年内将存在对ETP技术（乙醇/乙烯制丙烯）的经济需求。此外，新的研究直接指向甲醇和乙醇（或乙烯）联合转化为烯烃，如丙烯（METO），这在产物选择性和催化剂失活方面显示出协同效应。这种选择性的过程将是科学和经济上的突破。

In the context of climate change, dropping ethanol price and rising demand and price for ethylene and propylene, the development of new sustainable on-purpose methods for conversion of ethylene, (bio-)ethanol and methanol to “green” propylene and other olefins is a major task for this decade. Compared to “green” ethylene by Braskem for polymers industry, new methods to produce propylene and follow-up products for PP, PEG etc. have attracted considerable attention.From the current state of catalytic direct and hydrocarbon pool conversion of alcohols on zeolites, two major economic questions arise: (i) For different process conditions and catalyst materials, which conversion routes promote the desired product formation of propylene from methanol or ethanol? (ii) Which catalyst properties promote the desired conversion routes to a selective production of propylene from methanol, ethanol or both in mixture?In a more scientific point of view, the following questions will be investigated more deeply: (iii) Which catalytic surface reaction steps and which interdependent kinetics are necessary for a selective propylene formation? (iv) From thermodynamics, which process routes are dominantly driven by enthalpy, which by entropy and which are re-directed by pore geometry and morphology?The work program is splitted into zeolite synthesis and characterization, catalytic testing and mechanistic evaluation experiments. Beside solid-state characterization of catalysts (XRD, NMR, IR, SEM, EDX, ICP-OES, TPD), catalytic testing in a continuous mode will be combined with sophisticated mechanistic studies of adsorption kinetics (e.g. Howarth kinetics) and detailed hydrocarbon product networks (intermediates). As a specialty, new interdepending mechanistic conclusions of static reaction chain networks will be investigated by new mixed isotope scrambling experiments with D6-ethanol and 13C-methanol and GC/MS analysis. Despite to current discussions, it should reveal a dynamic competition of different direct and pool formation routes to propylene, in contrast to total exclusion of certain routes. Furthermore, the experiments will reveal highly selective parameter fields with respective deactivation behavior of catalysts. The knowledge-based control of the conversion routes will enable to design suitable catalysts for industry.With respect to current price developments, there is already a need for MTP technologies (methanol-to-propylene) and there will be an economic need for ETP technologies (ethanol/ethylene-to-propylene) within the next 5-10 years. Furthermore, new investigations direct to a combined methanol and ethanol (or ethylene) conversion to olefins, such as propylene (METO), which show synergistic effects in product selectivity and catalyst deactivation. Such a selective process would be a scientific and economic breakthrough.