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Improving the physicochemical properties of Y zeolite for catalytic cracking of heavy oil via sequential steam-alkali-acid treatments

机译:通过顺序蒸汽碱酸处理改善y沸石催化裂化催化裂化的物理化学性质

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In this study, modified Y zeolite with high catalytic activity and long lifetime was successfully prepared using sequential steam-alkali-acid treatments. Different alkali agents (NaOH, Na2CO3 and CaCO3 ) with various concentrations were used in order to improve the catalytic performance of the synthesized Y zeolite in heavy oil conversion process. The physicochemical properties of the prepared samples were investigated using XRD, FESEM, EDX, solid-state Si-29 and Al-27 NMR, BET, XRF, ICP, FTIR, and NH3 -TPD techniques. In addition, the properties of the deposited coke on the used catalysts were studied by FTIR and TGA-DTA techniques. Al extraction via steam treatment created Si-rich regions in the Y zeolite samples. Then, the Si elements were easily extracted from these Si-rich regions by using alkali treatment. In addition, acid washing with weak EDTA solution resulted in removal of extracted elements from the zeolite structure and pore opening after steam and alkali treatments. Combination of these treatments stimulated mesopores formation and improvement in textural properties for the Y zeolite samples. Structural and textural properties of Y zeolite were found to be preserved after sequential treatments. Catalytic performance of the prepared catalysts was investigated for the heavy oil catalytic cracking process in a fixed bed reactor. Regardless of the type of alkali agent used for sequential treatments, the heavy oil conversion and gasoline selectivity were strongly improved for all the modified catalysts in reference to the parent catalyst. The catalytic activity tests showed that sample treated with 1 M CaCO3 solution could secure a high heavy oil conversion (70%) and high selectivity towards gasoline and kerosene (45%). Furthermore, modification with CaCO3 inhibits coke formation significantly and enhanced the catalytic lifetime.
机译:在该研究中,使用序贯蒸汽碱酸性处理成功制备具有高催化活性和长寿命的改性Y沸石。使用具有各种浓度的不同碱剂(NaOH,Na 2 CO 3和CaCO 3)以改善重油转化过程中合成的Y沸石的催化性能。使用XRD,FESEM,EDX,固态Si-29和Al-27 NMR,BET,XRF,ICP,FTIR和NH3 -TPD技术研究制备样品的物理化学性质。此外,通过FTIR和TGA-DTA技术研究了沉积的焦炭上使用催化剂的性质。 Al萃取通过蒸汽处理在Y沸石样品中产生富含Si的地区。然后,通过使用碱处理容易从这些Si的区域中容易地提取Si元素。此外,具有弱EDTA溶液的酸洗涤导致从蒸汽和碱处理后从沸石结构和孔隙开口中除去萃取的元素。这些治疗的组合刺激了y沸石样品的造影性质的形成和改善。 y沸石的结构和纹理性质被发现在顺序处理后保存。研究了制备的催化剂的催化性能,用于固定床反应器中的重油催化裂化过程。无论用于序贯处理的碱金属剂如何,对母体催化剂的所有修饰的催化剂都强烈改善了重油转化和汽油选择性。催化活性试验表明,用1M CaCO 3溶液处理的样品可确保高重油转化(70%)和对汽油和煤油的高选择性(45%)。此外,用CaCO3的改性显着抑制焦炭形成并增强催化寿命。

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