Catalytic co-pyrolysis of switchgrass and polyethylene over HZSM-5: Catalyst deactivation and coke formation

Mullen, Charles A.; Dorado, Christina; Boateng, Akwasi A.

doi:10.1016/j.jaap.2017.11.012

Cited by 93 publications

(32 citation statements)

References 33 publications

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“…Within a same zeolite type, catalyst acidity can differ, as was investigated for different HZSM-5 catalysts with various Si/Al ratios [9]. Most of the studies carried out with zeolite catalysts mainly focus on comparative studies with various catalysts and operating conditions to understand their influence over the distribution and nature of yielded products, but few comprehensive works deal with involved cracking mechanisms and deactivation reactions [10][11][12].…”

Section: Zeolite Materialsmentioning

confidence: 99%

“…Among these chemical recycling processes, catalytic pyrolysis has been identified as a promising method for plastic waste revalorization, by converting polymers into basic chemicals used as feedstock [1,7,8]. Concerning the different catalysts used in pyrolysis and recycling processes, zeolites appear to be the most relevant catalysts used in the last decade [9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

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Deactivation and Regeneration of Zeolite Catalysts Used in Pyrolysis of Plastic Wastes—A Process and Analytical Review

2021

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In catalytic industrial processes, coke deposition remains a major drawback for solid catalysts use as it causes catalyst deactivation. Extensive study of this phenomenon over the last decades has provided a better understanding of coke behavior in a great number of processes. Among them, catalytic pyrolysis of plastics, which has been identified as a promising process for waste revalorization, is given particular attention in this paper. Combined economic and environmental concerns rose the necessity to restore catalytic activity by recovering deactivated catalysts. Consequently, various regeneration processes have been investigated over the years and development of an efficient and sustainable process remains an industrial challenge. Coke removal can be achieved via several chemical processes, such as oxidation, gasification, and hydrogenation. This review focuses on oxidative treatments for catalyst regeneration, covering the current progress of oxidation treatments and presenting advantages and drawbacks for each method. Molecular oxidation with oxygen and ozone, as well as advanced oxidation processes with the formation of OH radicals, are detailed to provide a deep understanding of the mechanisms and kinetics involved (direct and indirect oxidation, reaction rates and selectivity, diffusion, and mass transfer). Finally, this paper summarizes all relevant analytical techniques that can be used to characterize deactivated and regenerated solid catalysts: XRD, N2 adsorption-desorption, SEM, NH3-TPD, elemental analysis, IR. Analytical techniques are classified according to the type of information they provide, such as structural characteristics, elemental composition, or chemical properties. In function of the investigated property, this overall tool is useful and easy-to-use to determine the adequate analysis.

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Section: Zeolite Materialsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Deactivation and Regeneration of Zeolite Catalysts Used in Pyrolysis of Plastic Wastes—A Process and Analytical Review

2021

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“…The coke formation rate also depends on the type of used feedstock. Mullen et al [28] showed that the co-pyrolysis of biomass (switchgrass) and plastic waste (polyethylene) resulted in a reduction in the amount of deposited carbon. Polyethylene changes the reaction mechanism, providing additional hydrogen to the reaction medium.…”

Section: Formation Of Coke Depositmentioning

confidence: 99%

Catalyst Stability—Bottleneck of Efficient Catalytic Pyrolysis

Grams

Ruppert

2021

Catalysts

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The pyrolysis of lignocellulosic biomass is one of the most promising methods of alternative fuels production. However, due to the low selectivity of this process, the quality of the obtained bio-oil is usually not satisfactory and does not allow for its direct use as an engine fuel. Therefore, there is a need to apply catalysts able to upgrade the composition of the mixture of pyrolysis products. Unfortunately, despite the increase in the efficiency of the thermal decomposition of biomass, the catalysts undergo relatively fast deactivation and their stability can be considered a bottleneck of efficient pyrolysis of lignocellulosic feedstock. Therefore, solving the problem of catalyst stability is extremely important. Taking that into account, we presented, in this review, the most important reasons for catalyst deactivation, including coke formation, sintering, hydrothermal instability, and catalyst poisoning. Moreover, we discussed the progress in the development of methods leading to an increase in the stability of the catalysts of lignocellulosic biomass pyrolysis and strengthening their resistance to deactivation.

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“…Permanent deactivation is caused by changes to the zeolites structure at high temperatures, formation of stable coke species and/or poisoning of the acid sites by metals originating from the polymer itself [270]. Mullen et al [271] reported the co-pyrolysis of HDPE and switchgrass could mitigate the coke formation over HZSM-5 catalysts. Olefins generated from the catalytic pyrolysis of HDPE react with furanic compounds that originated from switchgrass to produce aromatic hydrocarbons and therefore reduce coke deposition.…”

Section: Catalyst Deactivation In Polymer Pyrolysismentioning

confidence: 99%

Catalytic Pyrolysis of Biomass and Polymer Wastes

et al. 2018

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Oil produced by the pyrolysis of biomass and co-pyrolysis of biomass with waste synthetic polymers has significant potential as a substitute for fossil fuels. However, the relatively poor properties found in pyrolysis oil—such as high oxygen content, low caloric value, and physicochemical instability—hampers its practical utilization as a commercial petroleum fuel replacement or additive. This review focuses on pyrolysis catalyst design, impact of using real waste feedstocks, catalyst deactivation and regeneration, and optimization of product distributions to support the production of high value-added products. Co-pyrolysis of two or more feedstock materials is shown to increase oil yield, caloric value, and aromatic hydrocarbon content. In addition, the co-pyrolysis of biomass and polymer waste can contribute to a reduction in production costs, expand waste disposal options, and reduce environmental impacts. Several promising options for catalytic pyrolysis to become industrially viable are also discussed.

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Catalytic co-pyrolysis of switchgrass and polyethylene over HZSM-5: Catalyst deactivation and coke formation

Cited by 93 publications

References 33 publications

Deactivation and Regeneration of Zeolite Catalysts Used in Pyrolysis of Plastic Wastes—A Process and Analytical Review

Deactivation and Regeneration of Zeolite Catalysts Used in Pyrolysis of Plastic Wastes—A Process and Analytical Review

Catalyst Stability—Bottleneck of Efficient Catalytic Pyrolysis

Catalytic Pyrolysis of Biomass and Polymer Wastes

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