In Situ Hydrothermal Conversion of Silica Gel Precursors to Binderless Zeolite X Pellets for Enhanced Olefin Adsorption

Jiang, Hao; Wang, Dan; Siang, Tan Ji; Chen, Yuxiang; An, Yang; Chen, Yonghao; Wu, Yuan; Sun, Hui; Shen, Benxian; Wu, Di; Liu, Jichang; Ling, Hao; Zhao, Jigang; Tong, Yujun

doi:10.22541/au.158137076.61130081

Cited by 2 publications

(2 citation statements)

References 56 publications

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“…24 This has been studied also in the adsorption application cases, where the gas streams containing olefins and CO 2 have been processed. 26 Treating the H forms of zeolites A and X with alkaline and some transition-metal chlorides at high temperatures has resulted in ion exchange between the metal ion and the H + in the zeolites. 27,28 Moreover, hot mixing of zeolite 13X with metal sulfates or soluble salts such as CuCl and CuCl 2 has resulted in improved ethylene adsorption selectivity and capacity.…”

Section: Reviewing the Process Concept: Operating And Materials Requi...mentioning

confidence: 99%

Miniplant-Scale Demonstration of Ethylene Adsorption Separation in Downstream of an Oxidative Coupling of Methane Process

Mokhtarani

Repke

Son

et al. 2021

Ind. Eng. Chem. Res.

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Developing an efficient sorbent and adopting an ethylene adsorption separation unit in downstream of an oxidative coupling of methane (OCM) process were the main focus of the present study. Since the mole fraction of the generated ethylene in the OCM reactor outlet is relatively low, the processing cost of the accompanying components and thereby the separation cost per ton of ethylene using the conventional cryogenic separation are insupportable. Zeolite 13X was modified in this research, demonstrating outstanding ethylene adsorption capacity and selectivity. The conducted adsorption experiments at a miniplant-scale unit enabled monitoring the adsorption breakthrough times and measuring the sorbents’ capacity under different operating pressures in the range of 1–5 bar while processing different feed flow and feed compositions, representing the attachment of the adsorption unit to different parts of the OCM process. The modified zeolite 13X showed superior performance than the reference sorbents such as zeolite 4A and activated carbon. Physical treatment of zeolite 13X, by calcining it at 550 °C, proved to be efficient in increasing its adsorption capacity. Chemically treating zeolite 13X via copper exchange on the other side increased its ethylene adsorption selectivity in competition to CO2 adsorption. In processing the CO2-rich feed streams (with the CO2 content 2.25 times of its C2H4 content), the Cu-exchanged zeolite 13X showed a promising ethylene adsorption capacity of 0.46 molC2H4 ·kgs –1 combined with an adsorption selectivity of 0.45 molC2H4 ·molCO2 . In processing the CO2-free feed streams (with the C2H4 content 2.75 times of its C2H6 content), using the calcined zeolite 13X secured the highest adsorption capacity of 1.4 molC2H4 ·kgs –1 along with an adsorption selectivity of 3.8 molC2H4 ·molC2H6 under 5 bar adsorption pressure. These indicate the promising potentials of the developed sorbents and the designed adsorption unit for processing the OCM reactor outlet gas stream before and after removal of its CO2 content.

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Section: Reviewing the Process Concept: Operating And Materials Requi...mentioning

confidence: 99%

Miniplant-Scale Demonstration of Ethylene Adsorption Separation in Downstream of an Oxidative Coupling of Methane Process

Mokhtarani

Repke

Son

et al. 2021

Ind. Eng. Chem. Res.

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“…Some other groups have also reported the preparation of binderless ZSM-5 zeolite using dry gel conversion method, transforming the amorphous precursors into a ZSM-5 zeolite phase with the assistance of the organic structure-directing agents. 17,18 These investigations have pointed to the feasibility of obtaining binderless catalysts. Nevertheless, the amount of acid sites of the as-synthesized binderless samples significantly decreased compared with the parent powder zeolite.…”

Section: Introductionmentioning

confidence: 99%

Structured Binder-Free Al-β Zeolite for Acid-Catalyzed Dehydration

Liu

Zhang

et al. 2021

ACS Appl. Nano Mater.

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It has long remained a challenge in catalysis to synthesize technical hierarchical nanosized zeolites without growth modifiers and binders. Herein, we report a facile synthetic route to directly prepare binderless hierarchical Al-β zeolite in shaped form, with retained acidity, and sufficient mechanical strengths. The preparation process consists of two steps, where an Al-β zeolite nanopowder is first shaped using tetraethyl orthosilicate; the extrudate is then recrystallized under hydrothermal conditions with the assistance of tetraethylammonium hydroxide (TEAOH) solution. The alkaline environment leads to mesopores into the zeolite, and transforms as well the SiO 2 binders into a zeolite framework. Several characterization methods were performed to reveal the structure−property relationships of the materials in powdered and shaped form. It was found that the process of TEAOH treatment is the combination of desilication, mesopore formation, and binder recrystallization to give zeolite Al-β nanoparticles, resulting in the obvious increase in microporosity, acidity, and X-ray diffraction crystallinity of samples. Density functional theory calculations were also used to rationalize the recrystallization process. Finally, the utility of the materials was demonstrated by evaluating their catalytic properties in the dehydration of 2-(4-ethylbenzoyl)benzoic acid, a reaction which is traditionally catalyzed by concentrated sulfuric acid and oleum. We found that the catalyst in technical form exhibits better catalytic performance than the powdered HB nanoparticles and higher product yield than traditional (homogeneous) catalysts.

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In Situ Hydrothermal Conversion of Silica Gel Precursors to Binderless Zeolite X Pellets for Enhanced Olefin Adsorption

Cited by 2 publications

References 56 publications

Miniplant-Scale Demonstration of Ethylene Adsorption Separation in Downstream of an Oxidative Coupling of Methane Process

Miniplant-Scale Demonstration of Ethylene Adsorption Separation in Downstream of an Oxidative Coupling of Methane Process

Structured Binder-Free Al-β Zeolite for Acid-Catalyzed Dehydration

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