(547a) Integrated Catalyst Design for the Conversion of Methanol and Syngas to Light Olefins over Hierarchical Zeolite-Based Composites

Light olefins, mainly ethylene and propylene, are the basic building blocks for various polymers and chemicals that serve a myriad of industries such as textiles, cosmetics, construction, automotive and aerospace. The global demand of ethylene and propylene was around 375 million tons in 2022 and is projected to grow around 4-5 % per year.¹ Conventional methods to produce light olefins include the steam cracking of ethane and naphtha, and as a by-product of fluid catalytic cracking of heavy hydrocarbons. The methanol-to-olefins (MTO) process has recently emerged as an alternative route for producing light olefins, with the first commercial plant launched in China in 2010 and several more built since.^2,3 This success has made the development of sustainable olefin production methods conceivable, including bio-olefins and direct bio-syngas-to-olefins (STO). Indeed, if methanol and syngas are produced from renewable processes like CO₂ hydrogenation and biomass conversion, olefin production can become more sustainable. Additionally, research interest in direct STO has been revived after previous challenges using traditional Fischer-Tropsch synthesis (FTS).³

However, one of the major issues in the MTO process is catalyst deactivation due to pore blocking by accumulation of coke.^2,3 Taking inspiration from the structure of leaves, we employ here a nature-inspired solution methodology to design hierarchically structured zeolites. In addition to their intrinsic micropores, hierarchically structured zeolites also possess meso- and macropores.⁴ Moreover, the effect of surface barriers on mass transport is investigated, as it can dominate overall mass transfer.⁵ Hierarchical structuring could facilitate selective diffusion within the zeolite and alleviate catalyst deactivation, thereby increasing the lifetime during the MTO process.⁴ The catalysts are characterized using a wide range of techniques, such as gas physisorption, XRD, ICP AES, NH₃-TPD and HRTEM. These hierarchically structured zeolites are tested for the direct conversion of syngas to olefins over a mixed catalyst bed that includes a metal oxide layer (for methanol synthesis) and a zeolite layer (for the MTO). Catalytic tests are conducted in a fixed-bed reactor and the performance of the synthesized catalysts are discussed.

[1] Zhu, H.; Babkoor, M.; Coppens, M.-O.; Materazzi, M. Fuel Process. Technol. 2025, 267, 108174.

[2] Tian, P.; Wei, Y.; Ye, M.; Liu, Z. ACS Catalysis. 2015, 1922–1938.

[3] Yarulina, I.; Chowdhury, A. D.; Meirer, F.; Weckhuysen, B. M.; Gascon, J. Nat. Catal 2018, 1, 398–411.

[4] Coppens, M.-O.; Weissenberger, T.; Zhang, Q.; Ye, G. Adv. Mater. Interfaces. 2021, 8, 2001409.

[5] S. Xu, K. Zheng, C.-R. Boruntea, D.-g. Cheng, F. Chen, G. Ye, X. Zhou, M.-O. Coppens, Chem. Soc. Rev. 2023, 52, 3991-4005.