Maximizing the production of high-value olefins from heavy crude oil is a crucial topic in the downstream refining industry. However, converting heavier fractions is a major challenge due to the small pore size of the zeolites. Therefore, this work aimed to develop extrudate zeolite catalysts posing adequate micromesoporous pore network and moderate acidity by combining microporous zeolite with the boehmite phase of alumina. These extruded zeolite-alumina catalysts are expected to allow sufficient diffusion of heavy fractions, thus leading to high cracking of heavy oil into valuable olefins. Different zeolite-alumina catalysts of varying alumina content ranging from 25 to 75% (AlZ-25, AlZ-50, and AlZ-75) were prepared in the laboratory to study the optimum zeolite-alumina ratios for maximum olefin production from heavy oil. The catalysts were characterized for their chemical and physical properties using nitrogen adsorption (N₂ adsorption), X-ray diffraction (XRD), inductively coupled plasma (ICP) spectrometry, Fourier transform infrared (FT-IR) spectroscopy, and NH₃ temperature programmed desorption (TPD). A gradual increase in the average pore diameter (APD) of the catalysts was observed due to the alumina ratio with a distinct range of acidity that is in the range of 125 to 375°C, and also the geometry of pores is not the same for all of the supports. Catalytic performance tests were conducted in a fixed-bed reactor at 450°C, 10 bar, and liquid hourly space velocity (LHSV) of 1 h⁻¹. The results revealed that the prepared catalysts were thermally stable and effective in heavy oil conversion to olefins. Moreover, the selectivity of propylene was higher than that of ethylene (P/E) due to the modified textural and acidic properties of the catalysts. The results showed that the catalysts prepared with moderate acidity and adequate mesopores exhibited a considerable effect on the conversion of heavy crude oil into olefins. Hence, the acidity and mesoporosity of the catalysts play a vital role in determining the catalyst performance.

中文翻译：

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重质原油制烯烃用微介孔沸石-氧化铝催化剂的合成

最大限度地利用重质原油生产高价值烯烃是下游炼油行业的一个重要课题。然而，由于沸石的孔径较小，转化较重的馏分是一项重大挑战。因此，这项工作旨在通过将微孔沸石与氧化铝的勃姆石相结合，开发具有足够微介孔孔网络和适度酸度的挤出沸石催化剂。预期这些挤出的沸石-氧化铝催化剂允许重馏分充分扩散，从而导致重油高度裂化成有价值的烯烃。在实验室中制备了氧化铝含量从 25% 到 75% 不等的不同沸石-氧化铝催化剂（AlZ-25、AlZ-50 和 AlZ-75），以研究从重油中最大程度地生产烯烃的最佳沸石-氧化铝比例。₂吸附）、X射线衍射（XRD）、电感耦合等离子体（ICP）光谱、傅里叶变换红外（FT-IR）光谱和NH ₃程序升温脱附（TPD）。由于氧化铝比率具有明显的酸度范围（在 125 至 375°C 范围内），因此观察到催化剂的平均孔径 (APD) 逐渐增加，并且孔的几何形状对于所有的支持。催化性能测试在固定床反应器中进行，温度为 450°C，压力为 10 bar，液时空速 (LHSV) 为 1 h ^-1. 结果表明，所制备的催化剂具有热稳定性，可有效地将重油转化为烯烃。此外，由于催化剂结构和酸性的改进，丙烯的选择性高于乙烯 (P/E)。结果表明，制备的酸度适中、介孔适中的催化剂对重质原油转化烯烃具有显着的影响。因此，催化剂的酸性和中孔率在决定催化剂性能方面起着至关重要的作用。