Hierarchical zeolites obtained by alkaline treatment for enhanced n-pentane catalytic cracking

Wang, Zijian; Zhang, Rongxin; Wang, Jieguang; Zhang, Yu; Xiang, Yanjuan; Kong, Lei; Liu, Hongquan; Ma, Aiyuan

doi:10.1016/j.fuel.2021.122669

Cited by 27 publications

(17 citation statements)

References 63 publications

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“…The electrostatic interaction through the inductive effect between the B acid Si–OH and the L acid creates a much stronger acid site in the OH group, and these inductive sites are stronger than the conventional B acid sites, thus leading to a significant increase in the amount of coke even in very little amounts. With a further increase of SLAS/SBAS, the n -hexane conversion activity decreases and therefore reduced the coke yield. , The olefin/paraffin shows that the hydrogen transfer reaction was inhibited with the improvement of SLAS/SBAS. In general, the ratio of SLAS/SBAS increases with the sodium loadings.…”

Section: Resultsmentioning

confidence: 99%

“…With a further increase of SLAS/SBAS, the n-hexane conversion activity decreases and therefore reduced the coke yield. 59,60 The olefin/paraffin shows that the hydrogen transfer reaction was inhibited with the improvement of SLAS/SBAS. In general, the ratio of SLAS/SBAS increases with the sodium loadings.…”

Section: Table 4 N-hexane Cracking Reaction Path and Related Thermody...mentioning

confidence: 99%

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Tuning the Concentrations of Acid Sites on ZSM-5 Zeolite for Improving Light Olefin Production in Catalytic Pyrolysis of Paraffin

Bai

Liu

Zhao

et al. 2022

Ind. Eng. Chem. Res.

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The influences of different B (Brønsted) acid site concentrations and the ratio of L (Lewis)/B (Brønsted) on the cracking pathways and product distributions in hexane cracking reactions as a model component of naphtha were investigated. The sodium-modified ZSM-5 catalysts were prepared by the wet impregnation method, and the Si–OH–Al groups of ZSM-5 were broken in the post-treatment process, resulting in a decrease in the number of strong B acid sites (SBAS) and an increase in the number of strong L acid sites (SLAS). The correlations between the n-hexane catalytic cracking reaction pathways and the catalyst acid properties were established. The reduced SBAS inhibits secondary reactions of light olefins such as hydrogen transfer, oligomerization, cyclization, and aromatization, while the increased SLAS and the ratio of SLAS/SBAS promoted the β scission reactions that significantly improved the yields of light olefins. Consequently, the appropriate SBAS and SLAS/SBAS ratios are desirable for the production of ethylene and propylene. The optimal SBAS concentration and SLAS/SBAS ratio ranged from 4.44 to 6.69 μmol/g and 9.18–11.86 for maximum ethylene and propylene yields of 16.14% and 14.63% in hexane catalytic pyrolysis reactions, respectively. Furthermore, the optimally prepared catalysts illustrated superior reactivities and catalytic stabilities in naphtha catalytic pyrolysis reactions under industrial conditions.

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Section: Resultsmentioning

confidence: 99%

Section: Table 4 N-hexane Cracking Reaction Path and Related Thermody...mentioning

confidence: 99%

Tuning the Concentrations of Acid Sites on ZSM-5 Zeolite for Improving Light Olefin Production in Catalytic Pyrolysis of Paraffin

Bai

Liu

Zhao

et al. 2022

Ind. Eng. Chem. Res.

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“…The catalytic cracking performance of zeolite is closely related to the its acidity and pore structure. , Several researchers demonstrated that the modification of alkaline (earth) metals on zeolite could optimize its pore structure and reduce the acid strength. − Zhang et al (2014) prepared a bifunctional catalyst by introducing alkaline metal oxide to zeolite for vacuum residue catalytic cracking. The overcracking issue has shown to be alleviated with the introduction of alkali due to a reduction of acidity.…”

Section: Basic Catalyst For Catalytic Cracking In Petroleum Refineriesmentioning

confidence: 99%

Research Progress of Basic Catalyst Used in Catalytic Cracking for Olefin Production and Heavy Oil Utilization

Gao

Zhang

Zhao

et al. 2023

Ind. Eng. Chem. Res.

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As the demand for light olefins increases and the oil becomes heavier, higher requirements for catalytic activity, anticoking performance, and stability of catalyst have been brought forward. Basic catalyst has attracted much more attention in recent years due to its excellent performance in heavy oil utilization. This review highlights the research progress of catalytic cracking over basic catalyst for olefin production and heavy oil utilization. The catalytic mechanism along with attractive functions of basic catalyst are summarized. The optimized condition of operation is discussed as well. Several processes and technologies of catalytic cracking over basic catalyst are introduced to advance future development. This review attempts to benefit new researchers in this field by helping them to understand basic-catalyzed cracking characteristics for preparing a suitable catalyst.

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“…Similarly, controllable desilication of ZSM-5 was achieved by mild alkaline treatment using NaHCO 3 to form hierarchical ZSM-5 with desired micro-and mesopores that minimize diffusion limitations and adjust the zeolite acidity, thus promoting n-pentane cracking to light olefins. 143 Ahmed et al 144 discovered that, during the desilication of ZSM-48 in 0.1 M NaOH, some aluminum dissolved into the alkaline solution, which was deposited as a layer of amorphous alumina on the zeolite framework. This layer decreased the crystallinity and porosity of the zeolite, and after it was removed by acid treatment (0.2 M HNO 3 ), both crystallinity and porosity were greatly enhanced.…”

Section: Catalyst Formulationsmentioning

confidence: 99%

“…However, the use of strong alkali solution has been linked to an uncontrollable pore size distribution and structural collapse. , Groen et al reported that the desilication approach is particularly effective at a certain Si/Al ratio within the range of 25–50 for the ZSM-5 zeolite. Similarly, controllable desilication of ZSM-5 was achieved by mild alkaline treatment using NaHCO 3 to form hierarchical ZSM-5 with desired micro- and mesopores that minimize diffusion limitations and adjust the zeolite acidity, thus promoting n -pentane cracking to light olefins …”

Section: Catalyst Formulationsmentioning

confidence: 99%

Catalytic Cracking of Crude Oil: Mini Review of Catalyst Formulations for Enhanced Selectivity to Light Olefins

Tanimu

Alasiri

et al. 2022

Energy Fuels

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The direct conversion of crude oil to light olefins is considered one the cheapest and most reliable sources of petrochemical primary feedstocks. Unlike in the past when refineries operated to produce mainly transportation fuels, such as gasoline and diesel, many refineries worldwide are considering tandem production of both fuels and chemicals (particularly, light olefins). To achieve this, refining technology, process optimization, and catalyst formulations may have to be reconfigured. Developing active and selective catalysts for crude oil cracking that fit into the current refinery system will go a long way in saving cost and time. In this review, catalyst formulations for the conversion of crude oil to light olefins have been discussed under the classifications: zeolite components, tuning of zeolite porosity, and matrix materials. USY has been the common zeolite that is used in the cracking of hydrocarbons to gasoline fractions, and ZSM-5 has the desired shape selectivity for cracking of paraffins in gasoline fractions to light olefins. At the same time, its low hydrogen transfer activity does not consume a large amount of generated light olefin, resulting in improvement of light olefin production. Various modifications of ZSM-5 composition have shown improvement in the light olefin yield. The wide range of hydrocarbons in crude oil makes pore size tuning of the zeolite especially important. Matrix materials generally increase the attrition resistance, hydrothermal and chemical stability, metal entrapment ability, coke resistivity, and fluidizable catalyst formation. However, they can also affect (positively or negatively) catalyst arrangement and active site properties, which makes careful selection very important.

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Hierarchical zeolites obtained by alkaline treatment for enhanced n-pentane catalytic cracking

Cited by 27 publications

References 63 publications

Tuning the Concentrations of Acid Sites on ZSM-5 Zeolite for Improving Light Olefin Production in Catalytic Pyrolysis of Paraffin

Tuning the Concentrations of Acid Sites on ZSM-5 Zeolite for Improving Light Olefin Production in Catalytic Pyrolysis of Paraffin

Research Progress of Basic Catalyst Used in Catalytic Cracking for Olefin Production and Heavy Oil Utilization

Catalytic Cracking of Crude Oil: Mini Review of Catalyst Formulations for Enhanced Selectivity to Light Olefins

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