Descriptors for High-Performance Nitrogen-Doped Carbon Catalysts in Acetylene Hydrochlorination

Order-in-disordered ultrathin carbon nanostructure with nitrogen-rich defects bridged by pseudographitic domains for high-performance ion capture

Carbon materials with defect-rich structure are highly demanded for various electrochemical scenes, but encountering a conflict with the deteriorative intrinsic conductivity. Herein, we build a highway-mediated nanoarchitecture that consists of the ordered pseudographitic nanodomains among disordered highly nitrogen-doped segments through a supramolecular self-assembly strategy. The "order-in-disorder" nanosheet-like carbon obtained at 800 °C (O/D NSLC-800) achieves a tradeoff with high defect degree (21.9 at% of doped nitrogen) and compensated electrical conductivity simultaneously. As expected, symmetrical O/D NSLC-800 electrodes exhibit superior capacitive deionization (CDI) performance, including brackish water desalination (≈82 mgNaCl g-1 at a cell voltage of 1.6 V in a 1000 mg L-1 NaCl solution) and reusage of actual refining circulating cooling water, outperforming most of the reported state-of-the-art CDI electrodes. The implanted pseudographitic nanodomains lower the resistance and activation energy of charge transfer, which motivates the synergy of hosting sites of multiple nitrogen configurations. Our findings shed light on electrically conductive nanoarchitecture design of defect-rich materials for advanced electrochemical applications based on molecular-level modulation.

Influence of Brönsted Acid Sites on Activated Carbon-Based Catalyst for Acetylene Dimerization

Activated carbon (AC) has been widely used as a support material with both tunable acidity and abundant functional groups for solid acid catalysts in various chemical processes such as acetylene dimerization. A facile, mild acid modification method that directly activates AC to generate rich defects and oxygen functional group surface structures with Brönsted acid sites and an enhanced conductivity is presented here. Impressively, the catalyst with optimized Brönsted acid sites and an enhanced dispersion of active components exhibited a superior acetylene dimerization catalytic activity. Moreover, theoretical calculations indicated that an increase in hydrogen concentration could inhibit the formation of coke. This research offered a feasible potential way to devise and construct a carbon-based solid acid catalyst with an excellent catalytic performance.

Reaction Environment Design for Multigram Synthesis via Sonogashira Coupling over Heterogeneous Palladium Single-Atom Catalysts

Single-atom heterogeneous catalysts (SACs) attract growing interest in their application in green chemistry and organic synthesis due to their potential for achieving atomic-level precision. These catalysts offer the possibility of achieving selectivity comparable to the traditionally applied organometallic complexes, while enhancing metal utilization and recovery. However, an understanding of SAC performance in organic reactions remains limited to model substrates, and their application as drop-in solutions may not yield optimal activity. Here, we investigate the previously unaddressed influence of the reaction environment, including solvent, base, cocatalyst, and ligand, on the performance of a palladium SAC in Sonogashira-Hagihara cross-couplings. By examining the effects of different solvents using the established criteria, we find that the behavior of the SAC deviates from trends observed with homogeneous catalysts, indicating a distinct interplay between heterogeneous systems and the reaction environment. Our results illustrate the satisfactory performance of SACs in cross-couplings of aryl iodides and acetylenes with electron-withdrawing and -donating groups, while the use of bromides and chlorides remains challenging. Extending the proof-of-concept stage to multigram scale, we demonstrate the synthesis of an intermediate of the anticancer drug Erlotinib. The catalyst exhibits high stability, allowing for multiple reuses, even under noninert conditions. Life-cycle assessment guides the upscaling of the catalyst preparation and quantifies the potential environmental and financial benefits of using the SAC, while also revealing the negligible impact of the PPh3 ligand and CuI cocatalyst. Our results underscore the significant potential of SACs to revolutionize sustainable organic chemistry and highlight the need for further understanding the distinct interplay between their performance and the reaction environment.

Defect-driven nanostructuring of low-nuclearity Pt-Mo ensembles for continuous gas-phase formic acid dehydrogenation

Supported metal clusters comprising of well-tailored low-nuclearity heteroatoms have great potentials in catalysis owing to the maximized exposure of active sites and metal synergy. However, atomically precise design of these architectures is still challenging for the lack of practical approaches. Here, we report a defect-driven nanostructuring strategy through combining defect engineering of nitrogen-doped carbons and sequential metal depositions to prepare a series of Pt and Mo ensembles ranging from single atoms to sub-nanoclusters. When applied in continuous gas-phase decomposition of formic acid, the low-nuclearity ensembles with unique Pt3Mo1N3 configuration deliver high-purity hydrogen at full conversion with unexpected high activity of 0.62 molHCOOH molPt-1 s-1 and remarkable stability, significantly outperforming the previously reported catalysts. The remarkable performance is rationalized by a joint operando dual-beam Fourier transformed infrared spectroscopy and density functional theory modeling study, pointing to the Pt-Mo synergy in creating a new reaction path for consecutive HCOOH dissociations.

Evidence of bifunctionality of carbons and metal atoms in catalyzed acetylene hydrochlorination

Carbon supports are ubiquitous components of heterogeneous catalysts for acetylene hydrochlorination to vinyl chloride, from commercial mercury-based systems to more sustainable metal single-atom alternatives. Their potential co-catalytic role has long been postulated but never unequivocally demonstrated. Herein, we evidence the bifunctionality of carbons and metal sites in the acetylene hydrochlorination catalytic cycle. Combining operando X-ray absorption spectroscopy with other spectroscopic and kinetic analyses, we monitor the structure of single metal atoms (Pt, Au, Ru) and carbon supports (activated, non-activated, and nitrogen-doped) from catalyst synthesis, using various procedures, to operation at different conditions. Metal atoms exclusively activate hydrogen chloride, while metal-neighboring sites in the support bind acetylene. Resolving the coordination environment of working metal atoms guides theoretical simulations in proposing potential binding sites for acetylene in the support and a viable reaction profile. Expanding from single-atom to ensemble catalysis, these results reinforce the importance of optimizing both metal and support components to leverage the distinct functions of each for advancing catalyst design.

New insights into nitrogen control strategies in sewage sludge pyrolysis toward environmental and economic sustainability

Sewage sludge (SS) contains a certain amount of nitrogen (N), resulting in various content of N in the pyrolysis products. Investigates on how to control the generation of NH₃ and HCN (deleterious gas-N species) or convert it to N₂ and maximize transforming N in sewage sludge (SS-N) into potentially valuable N-containing products (such as char-N and/or liquid-N) are of great significance for SS management. Understanding the nitrogen migration and transformation (NMT) mechanisms in SS during the pyrolysis process is essential for investigating the aforementioned issues. Therefore, in this review, the N content and species in SS are summarized, and the influencing factors during the SS pyrolysis process (such as temperature, minerals, atmosphere, and heating rate) that affect NMT in char, gas, and liquid products are analyzed. Furthermore, N control strategies in SS pyrolysis products are proposed toward environmental and economic sustainability. Finally, the state-of-the-art of current research and future prospects are summarized, with a focus on the generation of value-added liquid-N and char-N products, while concurrently reducing NO_x emission.

New Insights into N-Doped Porous Carbons as Both Heterogeneous Catalysts and Catalyst Supports: Opportunities for the Catalytic Synthesis of Valuable Compounds

Among the vast class of porous carbon materials, N-doped porous carbons have emerged as promising materials in catalysis due to their unique properties. The introduction of nitrogen into the carbonaceous matrix can lead to the creation of new sites on the carbon surface, often associated with pyridinic or pyrrolic nitrogen functionalities, which can facilitate various catalytic reactions with increased selectivity. Furthermore, the presence of N dopants exerts a significant influence on the properties of the supported metal or metal oxide nanoparticles, including the metal dispersion, interactions between the metal and support, and stability of the metal nanoparticles. These effects play a crucial role in enhancing the catalytic performance of the N-doped carbon-supported catalysts. Thus, N-doped carbons and metals supported on N-doped carbons have been revealed to be interesting heterogeneous catalysts for relevant synthesis processes of valuable compounds. This review presents a concise overview of various methods employed to produce N-doped porous carbons with distinct structures, starting from diverse precursors, and showcases their potential in various catalytic processes, particularly in fine chemical synthesis.

Recognizing the best catalyst for a reaction

Heterogeneous catalysis is immensely important, providing access to materials essential for the well-being of society, and improved catalysts are continuously required. New catalysts are frequently tested under different conditions making it difficult to determine the best catalyst. Here we describe a general approach to identify the best catalyst using a data set based on all reactions under kinetic control to calculate a set of key performance indicators (KPIs). These KPIs are normalized to take into account the variation in reaction conditions. Plots of the normalized KPIs are then used to demonstrate the best catalyst using two case studies: (i) acetylene hydrochlorination, a reaction of current interest for vinyl chloride manufacture, and (ii) the selective oxidation of methane to methanol using O₂ in water, a reaction that has attracted very recent attention in the academic literature.

Deactivation and Regeneration of Nitrogen Doped Carbon Catalyst for Acetylene Hydrochlorination

The poor stability of carbon materials doped with nitrogen limited their development in acetylene hydrochlorination. Therefore, investigating the deactivation reasons of carbon catalysts and researching regeneration methods became the research focus. Herein, carbon-nitrogen materials were synthesized by one-step pyrolysis, which using biomass materials with high nitrogen content, the synthesized material was used in an acetylene hydrochlorination reaction. The acetylene conversion rate of D-GH-800 catalyst was up to 99%, but the catalytic activity decreased by 30% after 60 h reaction. Thermogravimetric analysis results showed that the coke content was 5.87%, resulting in catalyst deactivation. Temperature-programmed desorption verified that the deactivation was due to the strong adsorption and difficult desorption of acetylene by the D-GH-800 catalyst, resulting in the accumulation of acetylene on the catalyst surface to form carbon polymers and leading to the pore blockage phenomenon. Furthermore, based on the catalyst deactivation by carbon accumulation, we proposed a new idea of regeneration by ZnCl₂ activation to eliminate carbon deposition in the pores of the deactivated catalyst. As a result, the activity of D-GH-800 was recovered, and lifetime was also extended. Our strategy illustrated the mechanism of carbon deposition, and the recoverability of the catalyst has promising applications.

The Effect of sp2 Content in Carbon on Its Catalytic Activity for Acetylene Hydrochlorination

We report the influence of sp² content in carbon catalyst on the catalytic activity for acetylene hydrochlorination. Nanodiamonds (NDs) were used as the precursor and calcinated under different temperatures. The resulting ND500, ND700, ND900, and ND1100 catalysts were characterized, and the sp² content increased with increasing calcination temperature. The specific activities of the catalysts first increased and then decreased with increasing sp² content. The highest catalytic activity could be obtained in the ND-900 catalyst with a sp² value of 43.9%. The density functional theory results showed that the adsorption sites for acetylene and hydrogen chloride were located at the interface between sp² and sp³ configuration.

Host-induced alteration of the neighbors of single platinum atoms enables selective and stable hydrogenation of butadiene

Tuning the coordination neighbors of the metal center is emerging as an elegant approach to manipulating the performance of supported single-atom catalysts in heterogeneous catalysis. Herein, atomically dispersed Pt species with different coordination neighbors hosted on nitrogen-doped carbon (NC) and graphitic carbon nitride (C₃N₄) are constructed through an impregnation-activation approach. Advanced characterization techniques including X-ray electron microscopy, X-ray absorption spectroscopy, and high angle annular dark-field scanning transmission electron microscopy reveal the different nature of active sites induced by the hosts: i.e., the Pt-N_x configuration in NC but both Pt-N and Pt-O coordinations in C₃N₄. H₂-D₂ exchange experiments and electron microscopy further evidence that Pt/NC exhibits a high propensity for H₂ splitting and high thermal stability of the Pt species against agglomeration, whereas Pt/C₃N₄ cannot dissociate H₂ and the Pt atoms easily aggregate in the reductive stream. Consequently, when applied in the selective hydrogenation of 1,3-butadiene, Pt/NC exhibits higher selectivity to butenes and excellent stability, but Pt/C₃N₄ behaves as a nanoparticle analogue favoring deep hydrogenation. The superior selectivity patterns of the single Pt atoms over Pt nanoparticles are rationalized by the inversed adsorption strength between the H₂ and 1,3-butadiene molecules at different metal sites, which is substantiated by the kinetic studies.

Performance descriptors of nanostructured metal catalysts for acetylene hydrochlorination

Controlling the precise atomic architecture of supported metals is central to optimizing their catalytic performance, as recently exemplified for nanostructured platinum and ruthenium systems in acetylene hydrochlorination, a key process for vinyl chloride production. This opens the possibility of building on historically established activity correlations. In this study, we derived quantitative activity, selectivity and stability descriptors that account for the metal-dependent speciation and host effects observed in acetylene hydrochlorination. To achieve this, we generated a platform of Au, Pt, Ru, Ir, Rh and Pd single atoms and nanoparticles supported on different types of carbon and assessed their evolution during synthesis and under the relevant reaction conditions. Combining kinetic, transient and chemisorption analyses with modelling, we identified the acetylene adsorption energy as a speciation-sensitive activity descriptor, further determining catalyst selectivity with respect to coke formation. The stability of the different nanostructures is governed by the interplay between single atom-support interactions and chlorine affinity, promoting metal redispersion or agglomeration, respectively.

Controlled Formation of Dimers and Spatially Isolated Atoms in Bimetallic Au-Ru Catalysts via Carbon-Host Functionalization

The introduction of a foreign metal atom in the coordination environment of single-atom catalysts constitutes an exciting frontier of active-site engineering, generating bimetallic low-nuclearity catalysts often exhibiting unique catalytic synergies. To date, the exploration of their full scope is thwarted by (i) the lack of synthetic techniques with control over intermetallic coordination, and (ii) the challenging characterization of these materials. Herein, carbon-host functionalization is presented as a strategy to selectively generate Au-Ru dimers and isolated sites by simple incipient wetness impregnation, as corroborated by careful X-ray absorption spectroscopy analysis. The distinct catalytic fingerprints are unveiled via the hydrogen evolution reaction, employed as a probe for proton adsorption properties. Intriguingly, the virtually inactive Au atoms enhance the reaction kinetics of their Ru counterparts already when spatially isolated, by shifting the proton adsorption free energy closer to neutrality. Remarkably, the effect is magnified by a factor of 2 in dimers. These results exemplify the relevance of controlling intermetallic coordination for the rational design of bimetallic low-nuclearity catalysts.

Redispersion strategy for high-loading carbon-supported metal catalysts with controlled nuclearity

Supported low-nuclearity metal catalysts integrating single atoms or small clusters have emerged as promising materials for diverse applications. While sophisticated synthetic methods provide a high level of nuclearity control in the subnanometre regime, these routes do not fulfil the requirements for translation into industrial practice of (i) effectiveness for high metal contents and (ii) facile scalability. Herein, we present a gas-phase redispersion strategy consisting of sequential C2H2 and HCl treatments to gradually disperse Ru, Rh and Ir nanoparticles supported on commercial activated carbon with metal content up to 10 wt% and initial average sizes of ≈ 1 nm into small clusters and eventually single atoms. Avoidance of nanoparticle surface overchlorination, which hinders C2H2 adsorption, is identified as key for the redispersion process, as demonstrated by the inefficacy of both C2H2-HCl cofeeding and inverse sequence (i.e., HCl first) treatments. Precise size control (±0.1 nm) is enabled by regulating the number of C2H2-HCl cycles. Detailed characterisation by X-ray absorption spectroscopy, electron paramagnetic resonance and time-resolved mass spectrometry reveals that the redispersion occurs via a layer-by-layer mechanism. Specifically, the migration of surface chlorinated metal species to the carbon support is induced by the C2H2 treatment, depleting accessible surface Cl atoms, while the subsequent HCl treatment rechlorinates the cluster surface. The strategy paves the way for the generation of high-density metal sites with tuneable nuclearity for tailored applications.

Bioderived Ionic Liquids and Salts with Various Cyano Anions as Precursors for Doped Carbon Materials

Carbohydrate moieties were combined with various cross-linkable anions (thiocyanate [SCN], tetracyanoborate [TCB], tricyanomethanide [TCM], and dicyanamide [DCA]) and investigated as precursors for the synthesis of nitrogen-doped and nitrogen-/sulfur-co-doped carbons. The influence of the molecular structures of the precursors on their thermophysical properties and the properties of the derived carbon materials was elucidated and compared to petroleum-derived analogs. A carbohydrate-based ionic liquid featuring an [SCN] anion yielded more carbon residues upon carbonization than its 1-ethyl-3-methylimidazolium analog, and the resulting dual-doping of the derived carbon material translated to enhanced catalytic activity in the oxygen reduction reaction.

Recent advances in metal-free heteroatom-doped carbon heterogonous catalysts

The development of cost-effective, efficient, and novel catalytic systems is always an important topic for heterogeneous catalysis from academia and industrial points of view. Heteroatom-doped carbon materials have gained more and more attention as effective heterogeneous catalysts to replace metal-based catalysts, because of their excellent physicochemical properties, outstanding structure characteristics, environmental compatibility, low cost, inexhaustible resources, and low energy consumption. Doping of heteroatoms can tailor the properties of carbons for different utilizations of interest. In comparison to pure carbon catalysts, these catalysts demonstrate superior catalytic activity in many organic reactions. This review highlights the most recent progress in synthetic strategies to fabricate metal-free heteroatom-doped carbon catalysts including single and multiple heteroatom-doped carbons and the catalytic applications of these fascinating materials in various organic transformations such as oxidation, hydrogenation, hydrochlorination, dehydrogenation, etc.

Design of carbon supports for metal-catalyzed acetylene hydrochlorination

For decades, carbons have been the support of choice in acetylene hydrochlorination, a key industrial process for polyvinyl chloride manufacture. However, no unequivocal design criteria could be established to date, due to the complex interplay between the carbon host and the metal nanostructure. Herein, we disentangle the roles of carbon in determining activity and stability of platinum-, ruthenium-, and gold-based hydrochlorination catalysts and derive descriptors for optimal host design, by systematically varying the porous properties and surface functionalization of carbon, while preserving the active metal sites. The acetylene adsorption capacity is identified as central activity descriptor, while the density of acidic oxygen sites determines the coking tendency and thus catalyst stability. With this understanding, a platinum single-atom catalyst is developed with stable catalytic performance under two-fold accelerated deactivation conditions compared to the state-of-the-art system, marking a step ahead towards sustainable PVC production.

Carbons are indispensable as supports for metal-based catalysts in polyvinyl chloride manufacture via acetylene hydrochlorination. In this work, the acetylene interaction, tunable through adjusting microporosity and oxygen sites is identified as central activity and stability descriptor.

Constructing green mercury-free catalysts with single pyridinic N species for acetylene hydrochlorination and mechanism investigation

A green bifunctional polymer for acetylene hydrochlorination is directly used as a catalyst and then used as a precursor to prepare an N-doped carbon catalyst.

Nitrogen-Doped Carbon-Assisted One-pot Tandem Reaction for Vinyl Chloride Production via Ethylene Oxychlorination

A bifunctional catalyst comprising CuCl2 /Al2 O3 and nitrogen-doped carbon was developed for an efficient one-pot ethylene oxychlorination process to produce vinyl chloride monomer (VCM) up to 76 % yield at 250 °C and under ambient pressure, which is higher than the conventional industrial two-step process (≈50 %) in a single pass. In the second bed, active sites containing N-functional groups on the metal-free N-doped carbon catalyzed both ethylene oxychlorination and ethylene dichloride (EDC) dehydrochlorination under the mild conditions. Benefitting from the bifunctionality of the N-doped carbon, VCM formation was intensified by the surface Cl*-looping of EDC dehydrochlorination and ethylene oxychlorination. Both reactions were enhanced by in situ consumption of surface Cl* by oxychlorination, in which Cl* was generated by EDC dehydrochlorination. This work offers a promising alternative pathway to VCM production via ethylene oxychlorination at mild conditions through a single pass reactor.

Single-Atom Catalysts across the Periodic Table

Isolated atoms featuring unique reactivity are at the heart of enzymatic and homogeneous catalysts. In contrast, although the concept has long existed, single-atom heterogeneous catalysts (SACs) have only recently gained prominence. Host materials have similar functions to ligands in homogeneous catalysts, determining the stability, local environment, and electronic properties of isolated atoms and thus providing a platform for tailoring heterogeneous catalysts for targeted applications. Within just a decade, we have witnessed many examples of SACs both disrupting diverse fields of heterogeneous catalysis with their distinctive reactivity and substantially enriching our understanding of molecular processes on surfaces. To date, the term SAC mostly refers to late transition metal-based systems, but numerous examples exist in which isolated atoms of other elements play key catalytic roles. This review provides a compositional encyclopedia of SACs, celebrating the 10th anniversary of the introduction of this term. By defining single-atom catalysis in the broadest sense, we explore the full elemental diversity, joining different areas across the whole periodic table, and discussing historical milestones and recent developments. In particular, we examine the coordination structures and associated properties accessed through distinct single-atom-host combinations and relate them to their main applications in thermo-, electro-, and photocatalysis, revealing trends in element-specific evolution, host design, and uses. Finally, we highlight frontiers in the field, including multimetallic SACs, atom proximity control, and possible applications for multistep and cascade reactions, identifying challenges, and propose directions for future development in this flourishing field.

Synergistic effect of two action sites on a nitrogen-doped carbon catalyst towards acetylene hydrochlorination

Whether the reaction pathway is steady or dynamic over the whole life cycle of a catalyst process can facilitate our understanding of its catalytic behavior. Herein, the dynamic reaction pathways of nitrogen-doped carbon catalysts are investigated in acetylene hydrochlorination. When triggered, the reaction follows the Langmuir-Hinshelwood mechanism with pyrrolic N and pyridinic N as dual active sites. However, pyridinic N is deactivated first, due to the strong adsorption of hydrogen chloride, causing the reaction to further run with pyrrolic N as the single active site and follow the Eley-Rideal mechanism. This work provides a new promising way to study the catalytic behavior of nitrogen-doped carbon catalysts.

Nanostructuring unlocks high performance of platinum single-atom catalysts for stable vinyl chloride production

A worldwide replacement of the toxic mercuric chloride catalyst in vinyl chloride manufacture via acetylene hydrochlorination is slowed down by the limited durability of alternative catalytic systems at high space velocities. Here, we demonstrate that platinum single atoms on carbon carriers are substantially more stable (up to 1073 K) than their gold counterparts (up to 473 K), enabling facile and scalable preparation and precise tuning of their coordination environment by simple temperature control. By combining kinetic analysis, advanced characterisation, and density functional theory, we assess how the Pt species determines the catalytic performance and thereby identify Pt(II)−Cl as the active site, being three times more active than Pt nanoparticles. Remarkably, we show that Pt single atoms exhibit outstanding stability in acetylene hydrochlorination and surpass the space-time-yields of their gold-based analogues after 25 h time-on-stream, qualifying as candidate for sustainable vinyl chloride production.

Active centre and reactivity descriptor of a green single component imidazole catalyst for acetylene hydrochlorination

A green catalyst for acetylene hydrochlorination yielding a VCM is presented using imidazole as a single component metal-free catalyst. The mechanisms and reactivities of imidazole-catalyzed acetylene hydrochlorination have been investigated by combined computational and experimental studies. The electronic effects of ortho-substituents on the reactivities have also been investigated. Through theoretical calculations and experimental studies, the nitrogen-atom including a lone pair active site of single component imidazole for metal-free acetylene hydrochlorination is proposed. It is suggested that the nitrogen-atom including a lone pair of imidazole adsorbs an HCl molecule to form an imidazole-HCl complex, which serves as the active catalyst to participate in the reaction process of acetylene hydrochlorination. Besides, the results show that C₂H₂ assists in the electrophilic addition of HCl, undergoing an almost planar six-membered ring transition state. Computational studies on the ortho-substitution of the active sites will have an important impact on the catalytic efficiency.

Nitrogen-doped porous carbon from biomass with superior catalytic performance for acetylene hydrochlorination

Acetylene hydrochlorination is an important aspect of the industrial synthesis of polyvinyl chloride, but it requires a toxic mercury chloride catalyst. Here we report a green, highly efficient and low cost nitrogen-doped soybean meal carbon (SBMC) catalyst obtained from the simple carbonization of biomass soybean meal (SBM) in the presence of zinc chloride. This material exhibits excellent catalytic performance during acetylene hydrochlorination, with an initial acetylene conversion greater than 99% and 98% selectivity for vinyl chloride at 200 °C over 110 h. Analyses by X-ray photoelectron spectroscopy and temperature programmed desorption as well as catalytic activity evaluations show that pyridinic species are the active sites for hydrogen chloride, while pyrrolic N species are the main active sites for acetylene. An analysis of charge calculations based on model catalysts further indicates that the activity of pyrrolic N species essentially determines the performance of the SBMC catalyst. This investigation of the mechanism of acetylene hydrochlorination over SBMC confirms that such nitrogen-doped catalysts have two different active sites for the adsorption and activation of hydrogen chloride and acetylene molecules. This mechanism is different from that associated with metal chloride catalysts such as HgCl₂. This SBMC catalyst is a potential alternative to HgCl₂@AC catalysts for vinyl chloride synthesis and suggests a new means of designing carbon catalysts with basic surfaces for acetylene hydrochlorination.

A green, highly efficient and low-cost nitrogen-doped soybean metal carbon (SBMC) catalyst obtained from the simple carbonization of biomass soybean meal (SBM) in the presence of zinc chloride.

Adsorption Behavior and Electron Structure Engineering of Pd-Based Catalysts for Acetylene Hydrochlorination

Adsorption and activation for substrates and the stability of Pd species in Pd-based catalysts are imperative for their wider adoption in industrial and practical applications. However, the influence factor of these aspects has remained unclear. This indicates a need to understand the various perceptions of the structure–function relationship that exists between microstructure and catalytic performance. Herein, we revisit the catalytic performance of supported-ionic-liquid-phase stabilized Pd-based catalysts with nitrogen-containing ligands as a promoter for acetylene hydrochlorination, and try to figure out their regulation. We found that the absolute value of the differential energy, |Eads(C2H2)-Eads(HCl)|, is negative correlated with the stability of palladium catalysts. These findings imply that the optimization of the electron structure provides a new strategy for designing highly active yet durable Pd-based catalysts.