Metrics of performance relevant in methanol-to-hydrocarbons catalysis

Shi, Zhichen; Bhan, Aditya

doi:10.1016/j.jcat.2023.03.022

Cited by 7 publications

(4 citation statements)

References 79 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Such a product distribution suggests lower prevalence of the arene with respect to alkene-chain carries and less prominent HT reactions when the D-methanol feed is used. Since formation of polycyclic aromatics hydrocarbons (PAHs) is primarily ascribed to the overgrowth of the arene species in which HT reactions play the central role, − these product distribution patterns indicate that slower catalyst deactivation in the presence of D-methanol may arise not only from its lower reactivity with respect to H-methanol, but also from the variable kinetic sensitivity of different reactions of the MTH network to these isotopologues.…”

Section: Resultsmentioning

confidence: 99%

How Micropore Topology Influences the Structure and Location of Coke in Zeolite Catalysts

Rzepka,

Sheptyakov,

Wang

et al. 2024

ACS Catal.

View full text Add to dashboard Cite

Zeolite catalysts exhibit microporous structures, akin to the pockets in naturally occurring enzyme catalysts, which enable the confinement of reaction intermediates, thus facilitating chemical transformations. Nonetheless, the micropores also influence the formation of coke species, which is the main source of catalytic activity loss. Unveiling the relationships between the micropore topology and the internal structure and location of deactivating coke compounds is of high relevance for comprehending the deactivation mechanisms. In this study, we used an approach exploiting powder neutron diffraction to assess the location of coke and determine the dominating structures in the topologically distinct ZSM-5 (MFI topology), ZSM-35 (FER), and SSZ-13 (CHA) zeolite catalysts deactivated in industrially relevant methanol-to-hydrocarbon (MTH) conversion. In ZSM-5 and ZSM-35 catalysts, coke resides along the straight 10-membered ring (MR) channels and exhibits the highest concentration in their intersecting regions with sinusoidal 10 MR and straight 8 MR pores, respectively. In the SSZ-13 catalyst, coke is not only located in cages but also protrudes through their 8 MR windows, suggesting the interconnectivity of coke molecules between the large cavities. Notably, the coke-associated signals in the ZSM-5 and ZSM-35 catalysts show a strong planar arrangement that can be fitted by polycyclic and monocyclic arene structures, respectively. These averaged coke structures are consistent with the composition of coke assessed by gas chromatography−mass spectrometry, 13 C and two-dimensional 1 H double-quantum single-quantum magic-angle spinning nuclear magnetic resonance, and operando diffuse reflectance ultraviolet−visible spectroscopic analysis. The findings evidence that the pore topology directs the confinement and structure of coke, wherein the largest void zones of the micropore space are the most susceptible to coking.

show abstract

Section: Resultsmentioning

confidence: 99%

How Micropore Topology Influences the Structure and Location of Coke in Zeolite Catalysts

Rzepka,

Sheptyakov,

Wang

et al. 2024

ACS Catal.

View full text Add to dashboard Cite

show abstract

“…This Review highlights the opportunities, challenges, prior learnings, and future research in the zeolites/zeotypes catalytic function for the direct conversion of CO x to valuable products via oxygenate intermediates. There are recent reviews regarding the advances in C 1 catalysis, ,, CO 2 to methanol, ,, and methanol to hydrocarbons (MTH), ,− demonstrating the relevance and importance of these research fields. Nonetheless, there has not yet been a critical discussion of the zeolite/zeotype catalytic function in the context of CO x valorization using tandem catalysis.…”

Section: Introductionmentioning

confidence: 99%

The Oxygenate-Mediated Conversion of CO_x to Hydrocarbons─On the Role of Zeolites in Tandem Catalysis

Xie,

Olsbye

2023

Chem. Rev.

View full text Add to dashboard Cite

Decentralized chemical plants close to circular carbon sources will play an important role in shaping the postfossil society. This scenario calls for carbon technologies which valorize CO 2 and CO with renewable H 2 and utilize process intensification approaches. The single-reactor tandem reaction approach to convert CO x to hydrocarbons via oxygenate intermediates offers clear benefits in terms of improved thermodynamics and energy efficiency. Simultaneously, challenges and complexity in terms of catalyst material and mechanism, reactor, and process gaps have to be addressed. While the separate processes, namely methanol synthesis and methanol to hydrocarbons, are commercialized and extensively discussed, this review focuses on the zeolite/zeotype function in the oxygenate-mediated conversion of CO x to hydrocarbons. Use of shape-selective zeolite/ zeotype catalysts enables the selective production of fuel components as well as key intermediates for the chemical industry, such as BTX, gasoline, light olefins, and C 3+ alkanes. In contrast to the separate processes which use methanol as a platform, this review examines the potential of methanol, dimethyl ether, and ketene as possible oxygenate intermediates in separate chapters. We explore the connection between literature on the individual reactions for converting oxygenates and the tandem reaction, so as to identify transferable knowledge from the individual processes which could drive progress in the intensification of the tandem process. This encompasses a multiscale approach, from molecule (mechanism, oxygenate molecule), to catalyst, to reactor configuration, and finally to process level. Finally, we present our perspectives on related emerging technologies, outstanding challenges, and potential directions for future research. CONTENTS 1. Introduction 11775 2. Methanol-Mediated CO x Conversion to Hydrocarbons 11783 2.1. A Short Introduction to the MTH Process 11783 2.2. Integration of the MTH Reactions with CO x Hydrogenation 11787 3. Dimethyl-Ether-Mediated CO x Conversion to Hydrocarbons 11791 3.1. Dimethyl Ether to Hydrocarbons (DTH) 11791 3.2. Methanol to Dimethyl Ether (MTD) 11793 3.3. Integration of the MTD and DTH Reactions with CO x Hydrogenation 11794 4. Ketene-Mediated CO x Conversion to Hydrocarbons 11798 4.1. Methanol Carbonylation 11798 4.2. DME Carbonylation 11799 4.3. Integration of Methanol and DME Carbonylation with CO x Hydrogenation 11803 5.

show abstract

“…It has been recognized that MTO conversion proceeds via the intricate hydrocarbon pool (HCP) mechanism in zeolites. − In addition to the intrinsic Brønsted acidic sites, the retained organics, known as HCPs, act as cocatalysts to produce light olefins. , Tremendous effects have been devoted to unraveling the veil of HCPs during the reaction by a variety of characterization, computational, and kinetic investigations. − In general, both aromatics and olefins have been suggested as the dominating HCPs to participate in the reaction, and the so-called aromatic-based and olefin-based cycles thus are responsible for the formation of light olefins. − Both aromatic-based and olefin-based cycles are essentially the same thing and consist of (side) chain propagation and elimination of olefins. , It is currently found that the catalytic performance of the MTO conversion, especially the product distribution, depends highly on the contribution of each cycle. − It was reported that the MTO selectivity directly relates to the methylation degree of the retained polymethylbenzenes (polyMBs), and the preferential stabilization of the fully methylated HCPs favors the aromatic-based paring cycle. , The olefin-based cycle, on the other hand, favors the formation of propene and higher olefins by successive methylation and cracking steps . As a consequence, the catalytic performance of the MTO conversion could be possibly optimized in a controllable manner if the distribution of HCPs and the contribution of each cycle governed by zeolite structures under operating conditions could be quantified and tailored . However, the dynamic characteristics of HCPs formed in situ engendered severe challenges to identify the structures and track the evolution of dominating HCPs in detail during the reaction, let alone the complexity of the involved reaction pathways.…”

Section: Introductionmentioning

confidence: 99%

“…21 As a consequence, the catalytic performance of the MTO conversion could be possibly optimized in a controllable manner if the distribution of HCPs and the contribution of each cycle governed by zeolite structures under operating conditions could be quantified and tailored. 46 However, the dynamic characteristics of HCPs formed in situ engendered severe challenges to identify the structures and track the evolution of dominating HCPs in detail during the reaction, let alone the complexity of the involved reaction pathways. First-principles microkinetic simulations have offered great merits to establish the relations between the energetics calculated at the atomic scale and the catalytic performances at the macroscopic scale in heterogeneous catalysis.…”

Section: Introductionmentioning

confidence: 99%

Microkinetic Simulations of Methanol-to-Olefin Conversion in H-SAPO-34: Dynamic Distribution and Evolution of the Hydrocarbon Pool and Implications for Catalytic Performance

et al. 2023

ACS Catal.

View full text Add to dashboard Cite

The dominating hydrocarbon pool species (HCPs) in zeolites for methanol-to-olefin (MTO) conversion have been the subject of intense debate for decades due to the diversity of structures and the complexity of reaction networks. We performed microkinetic simulations in a three-site model to study the MTO conversion in industrially relevant H-SAPO-34 zeolite under a wide range of operating conditions. The energetics of 229 and 342 elementary reaction steps were employed, respectively, in the aromatic-based and olefin-based cycles. The dynamic distribution and evolution of the retained aromatic or olefinic HCPs and the origin of olefin products were revealed with respect to reaction conditions. We corroborate that the olefin-based cycle dominates the MTO conversion in H-SAPO-34 under most reaction conditions, and the contribution of the aromatic-based cycle increase with increasing temperature, decreasing pressure, and/or decreasing water partial pressure. The paring route, dedicated highly to propene formation, prevails in the aromatic-based cycle; the side chain route, favoring exclusively ethene formation, only prevails at extremely lower temperatures, higher pressures, and higher water contents. The inherent activity of each aromatic HCP via the paring cycle increases, while its population retained in H-SAPO-34 usually decreases, with the methylation degree remarkably from tetramethylbenzene to hexamethylbenzene. The contents of higher methylbenzenes increase with decreasing water partial pressure, leading to the enhanced contribution of the aromatic-based cycle. The olefin-based cycle contributes to the formation of both ethene and other olefins, and the product distribution is drastically sensitive to reaction conditions. Ethene predominantly comes from the cracking of C5 and C6 species, and propene comes from C5 to C7 species. The olefin-based cycle shifts from the interconversion of C2–C7 olefins toward C2–C5 ones with increasing temperature and water partial pressure to enhance ethene formation. Under industrially relevant conditions, the conversion rate of methanol via the olefin-based cycle is 40-fold greater than that via the aromatic-based cycle (6.6 vs 0.15 s–1), and the former agrees unexpectedly with the experimental value in low-silica AlPO-34 (7.0 s–1). This work thus solves the puzzle of dominating HCPs as a function of reaction conditions in H-SAPO-34 and provides mechanistic insights into the kinetic behaviors, which are the basis for the optimization of the MTO catalyst and process.

show abstract

Metrics of performance relevant in methanol-to-hydrocarbons catalysis

Cited by 7 publications

References 79 publications

How Micropore Topology Influences the Structure and Location of Coke in Zeolite Catalysts

How Micropore Topology Influences the Structure and Location of Coke in Zeolite Catalysts

The Oxygenate-Mediated Conversion of CO_x to Hydrocarbons─On the Role of Zeolites in Tandem Catalysis

Microkinetic Simulations of Methanol-to-Olefin Conversion in H-SAPO-34: Dynamic Distribution and Evolution of the Hydrocarbon Pool and Implications for Catalytic Performance

Contact Info

Product

Resources

About

Metrics of performance relevant in methanol-to-hydrocarbons catalysis

Cited by 7 publications

References 79 publications

How Micropore Topology Influences the Structure and Location of Coke in Zeolite Catalysts

How Micropore Topology Influences the Structure and Location of Coke in Zeolite Catalysts

The Oxygenate-Mediated Conversion of COx to Hydrocarbons─On the Role of Zeolites in Tandem Catalysis

Microkinetic Simulations of Methanol-to-Olefin Conversion in H-SAPO-34: Dynamic Distribution and Evolution of the Hydrocarbon Pool and Implications for Catalytic Performance

Contact Info

Product

Resources

About

The Oxygenate-Mediated Conversion of CO_x to Hydrocarbons─On the Role of Zeolites in Tandem Catalysis