Aromatics Production via Methanol-Mediated Transformation Routes

Unraveling Spatially Dependent Hydrophilicity and Reactivity of Confined Carbocation Intermediates during Methanol Conversion over ZSM-5 Zeolite

Carbocations play a pivotal role as reactive intermediates in zeolite-catalyzed methanol-to-hydrocarbon (MTH) transformations. However, the interaction between carbocations and water vapor and its subsequent effects on catalytic performance remain poorly understood. Using micro-magnetic resonance imaging (μMRI) and solid-state NMR techniques, this work investigates the hydrophilic behavior of cyclopentenyl cations within ZSM-5 pores under vapor conditions. We show that the polar cationic center of cyclopentenyl cations readily initiates water nucleus formation through water molecule capture. This leads to an inhomogeneous water adsorption gradient along the axial positions of zeolite, correlating with the spatial distribution of carbocation concentrations. The adsorbed water promotes deprotonation and aromatization of cyclopentenyl cations, significantly enhancing the aromatic product selectivity in MTH catalysis. These results reveal the important influence of adsorbed water in modulating the carbocation reactivity within confined zeolite pores.

Combined Strategies Enable Highly Selective Light Olefins and -Xylene Production on Single Catalyst Bed

Achieving multiple high-value-added chemical production through novel reaction processes and shape-selective catalytic strategy is the key to realizing efficient low-carbon catalytic processes. In this work, a methanol-toluene coreaction system was developed, and combined control strategies of reaction pathway guidance and shape-selective catalysis were applied for the successful production of light olefins and para-xylene on single HZSM-5 catalyst bed. Cofeeding toluene additionally provides reactive and flowing aromatic hydrocarbon pool species that change the dominant reaction pathway in the complex network of the methanol reaction on HZSM-5 and promote the formation of ethylene. For the first time, the key reaction intermediates methylmethylenecyclodiene are directly captured and identified by experimental and theoretical techniques. This helps to propose the catalytic cycle for the dominant generation of ethylene and, more importantly, enriches the methanol-to-hydrocarbons (MTH) chemistry and hydrocarbon pool mechanism. Furthermore, 0.4HZSM-5@S-1-CLD, an optimized HZSM-5 catalyst modified by the silicalite-1 epitaxial growth followed by silanization approach, realizes highly selective production of light olefins (especially ethylene) and para-xylene, while excellent reactant activity is maintained. This highly efficient coreaction route gives an important leading significance in synthesizing the raw materials for the polyolefin and polyester industries. The establishment of the combined control strategies provides a model for the joint production of multiple target chemicals in complex catalytic processes.

Nanometric Cu-ZnO Particles Supported on N-Doped Graphitic Carbon as Catalysts for the Selective CO2 Hydrogenation to Methanol

The quest for efficient catalysts based on abundant elements that can promote the selective CO2 hydrogenation to green methanol still continues. Most of the reported catalysts are based on Cu/ZnO supported in inorganic oxides, with not much progress with respect to the benchmark Cu/ZnO/Al2O3 catalyst. The use of carbon supports for Cu/ZnO particles is much less explored in spite of the favorable strong metal support interaction that these doped carbons can establish. This manuscript reports the preparation of a series of Cu-ZnO@(N)C samples consisting of Cu/ZnO particles embedded within a N-doped graphitic carbon with a wide range of Cu/Zn atomic ratio. The preparation procedure relies on the transformation of chitosan, a biomass waste, into N-doped graphitic carbon by pyrolysis, which establishes a strong interaction with Cu nanoparticles (NPs) formed simultaneously by Cu2+ salt reduction during the graphitization. Zn2+ ions are subsequently added to the Cu-graphene material by impregnation. All the Cu/ZnO@(N)C samples promote methanol formation in the CO2 hydrogenation at temperatures from 200 to 300 °C, with the temperature increasing CO2 conversion and decreasing methanol selectivity. The best performing Cu-ZnO@(N)C sample achieves at 300 °C a CO2 conversion of 23% and a methanol selectivity of 21% that is among the highest reported, particularly for a carbon-based support. DFT calculations indicate the role of pyridinic N doping atoms stabilizing the Cu/ZnO NPs and supporting the formate pathway as the most likely reaction mechanism.

Implications in the production of defossilized methanol: A study on carbon sources

The transition of the current fossil based chemical industry to a carbon-neutral industry can be done by the substitution of fossil carbon for defossilized carbon in the production of base chemicals. Methanol is one of the seven base chemicals, which could be used to produce other base chemicals (light olefins and aromatics). In this research, we evaluated the synthesis of methanol based on defossilized carbon sources (maize, waste biomass, direct air capture of CO2 (DAC), and CO2 from the cement industry) by considering carbon source availability, energy, water, and land demand. This evaluation was based on a carbon balance for each of the carbon sources. Our results show that maize, waste biomass, and CO2 cement could supply 0.7, 2, 15 times the carbon demand for methanol respectively. Regarding the energy demand maize, waste biomass, DAC, and CO2 from cement demand 25, 21, 48, and 45GJtonMeOH separately. The demand for water is 5300, 220, 8, and 8m3tonMeOH. And lastly, land demand was estimated to 1031, 36, 83, and 77m2tonMeOH per carbon source. The high-demanding-resource production of defossilized methanol is dependent on the availability of resources per location. Therefore, we analyzed the production of defossilized methanol in the Netherlands, Saudi Arabia, China, and the USA. China is the only country where CO2 from the cement industry could provide all the demand of carbon. But as we envision society becoming carbon neutral, CO2 from the cement industry would diminish in time, as a consequence, it would not be sufficient to supply the demand for carbon. DAC would be the only source able to provide the demand for defossilized carbon.

A density functional theory study on the mechanism of toluene from dimethylcyclopentane catalyzed by the [GaH]2+ active site of Ga-ZSM-5

The ONIOM (ωb97xd/6-31G(d,p):pm6) method was used to study the reaction mechanism of dimethylcyclopentane to toluene by the [GaH]2+ active site of Ga-ZSM-5. The results showed that the rate-determining step in the dimethylcyclopentane aromatization process is the ring expansion process. Compared to those of methylcyclopentane to benzene (D. D. Zhang, H. Y. Liu, L. X. Ling, H. R. Zhang, R. G. Zhang, P. Liu and B. J. Wang, Phys. Chem. Chem. Phys., 2021, 23, 10988-11003.), the free energy barriers of dimethylcyclopentane to toluene are significantly decreased, indicating that toluene is easier to produce than benzene, which confirmed the experimental results that a higher proportion of toluene than benzene is produced in the MTA process.

Accelerated Synthesis of Nanolayered MWW Zeolite by Interzeolite Transformation

Hierarchical zeolites can offer substantial benefits over bulk zeolites in catalysis. A drawback towards practical implementation is their lengthy synthesis, often requiring complex organic templates. This work describes an accelerated synthesis of nanolayered MWW zeolite based on the combination of interzeolite transformation (IZT) with a dual-templating strategy. FAU zeolite, hexamethyleneimine (HMI), and cetyltrimethylammonium bromide (CTAB) were respectively employed as Al source and primary zeolite, structure directing agent, and exfoliating agent. This approach allowed to reduce the synthesis of nanolayered MWW to 48 h, which is a considerable advance over the state of the art. Tracking structural, textural, morphological, and chemical properties during crystallization showed that 4-membered-ring (4MR) units derived from the FAU precursor are involved in the faster formation of MWW in comparison to a synthesis procedure from amorphous precursor. CTAB restricts the growth of the zeolite in the c-direction, resulting in nanolayered MWW. Moreover, we show that this approach can speed up the synthesis of nanolayered FER. The merits of nanolayered MWW zeolites are demonstrated in terms of improved catalytic performance in the Diels-Alder cycloaddition of 2,5-dimethylfuran and ethylene to p-xylene compared to bulk reference MWW sample.

Enabling the Methanol Economy: Opportunities and Challenges for Heterogeneous Catalysis in the Production of Liquid Fuels via Methanol

ConspectusThirty years ago, George A. Olah proposed the concept of the methanol economy, where methanol replaces fossil fuels as a means of energy storage, ground transportation fuel, and raw material for the manufacture of other carbon-based products. Over the years, with rising global warming concerns, the concept has evolved. A special interest is devoted to the development of catalytic processes that allow the transformation of carbon dioxide, via methanol, into CO2 neutral liquid hydrocarbons. These products could replace the oil-based fuels currently used by combustion engines. The rapid depletion of such fuels would avoid a considerable amount of CO2 emissions during the current energy transition.Over the past decade, we have focused on different key processes that should allow for maximal atom efficiency and, therefore, minimal energy consumption in a field, CO2 valorization, that can easily become a zero-sum game. In this Account, we highlight the importance of catalyst design to overcome the process challenges in the production of liquid fuels from methanol. Additionally, progress in multifunctional catalysts able to directly convert, in one single reactor, CO2 to liquid fuels is also discussed in detail. This integrated option is of particular interest since it allows an important decrease in operational units while increasing throughput by converting, in situ, a thermodynamically limited intermediate.

Evaluating the efficacy of zeolites synthesized from natural clay for the methanol-to-hydrocarbon process

Introducing sustainability into advanced catalytic material design is essential to address growing environmental concerns. Among them, synthesizing inorganic zeolite materials from non-traditional sources (like natural clay) offers several advantages, contributing to sustainability and environmental stewardship. With this objective, we used kaolin to synthesize zeolites with different topologies: SSZ-13 (8-MR with CHA topology), ZSM-5 (10-MR with MFI topology), and Beta (12-MR with BEA topology) (MR: member ring), where a simple and flexible synthetic protocol was adopted without any significant changes. All these zeolites were subjected to catalytic performance evaluation concerning the industrially relevant methanol-to-hydrocarbon (MTH) process. Herein, the kaolin-derived zeolites, especially ZSM-5, led to superior performance and demonstrated enhanced catalyst deactivation-resistant behavior compared to their zeolite counterparts prepared from traditional synthetic routes. Various characterization tools (including under operando conditions) were employed to understand their reactions and deactivation mechanisms. Overall, making zeolites from non-traditional sources presents a pathway for sustainable and environmentally friendly material production, offering benefits such as reduced resource dependence, lower energy consumption, and tailored physicochemical properties beneficial to catalysis. In a broader context, such a research approach contributes to the transition toward a more sustainable and circular economy.

Interplay Between Particle Size and Hierarchy of Zeolite ZSM-5 During the CO2 -to-aromatics Process

The CO2 -to-aromatics process is a chemical reaction that converts carbon dioxide (CO2 ) into valuable petrochemical, i. e., aromatics (especially, benzene, toluene, and xylene) over the metal/zeolite bifunctional catalytic systems. These aromatics are used in producing plastics, fibers, and other industrial products, which are currently exclusively sourced from fossil-derived feedstocks. The significance of this process lies in its potential to mitigate climate change by reducing greenhouse gas emissions and simultaneously producing valuable chemicals. Consequently, these CO2 -derived aromatics can reduce the reliance on fossil fuels as a source of feedstocks, which can help to promote a more sustainable and circular economy. Owing to the existence of a wider straight channel favoring the aromatization process, zeolite ZSM-5 is extensively used to yield aromatics during CO2 hydrogenation over bifunctional (metal/zeolite) catalytic systems. To provide a better understanding of this unique property of zeolite ZSM-5, this work investigates the impact of particle size and hierarchy of the zeolite and how these govern the reaction performance and the overall selectivity. As a result, an improved understanding of the zeolite-catalyzed hydrocarbon conversion process has been obtained.

Awareness raising and dealing with methanol poisoning based on effective strategies

Intoxication with methanol most commonly occurs as a consequence of ingesting, inhaling, or coming into contact with formulations that include methanol as a base. Clinical manifestations of methanol poisoning include suppression of the central nervous system, gastrointestinal symptoms, and decompensated metabolic acidosis, which is associated with impaired vision and either early or late blindness within 0.5-4 h after ingestion. After ingestion, methanol concentrations in the blood that are greater than 50 mg/dl should raise some concern. Ingested methanol is typically digested by alcohol dehydrogenase (ADH), and it is subsequently redistributed to the body's water to attain a volume distribution that is about equivalent to 0.77 L/kg. Moreover, it is removed from the body as its natural, unchanged parent molecules. Due to the fact that methanol poisoning is relatively uncommon but frequently involves a large number of victims at the same time, this type of incident occupies a special position in the field of clinical toxicology. The beginning of the COVID-19 pandemic has resulted in an increase in erroneous assumptions regarding the preventative capability of methanol in comparison to viral infection. More than 1000 Iranians fell ill, and more than 300 of them passed away in March of this year after they consumed methanol in the expectation that it would protect them from a new coronavirus. The Atlanta epidemic, which involved 323 individuals and resulted in the deaths of 41, is one example of mass poisoning. Another example is the Kristiansand outbreak, which involved 70 people and resulted in the deaths of three. In 2003, the AAPCC received reports of more than one thousand pediatric exposures. Since methanol poisoning is associated with high mortality rates, it is vital that the condition be addressed seriously and managed as quickly as feasible. The objective of this review was to raise awareness about the mechanism and metabolism of methanol toxicity, the introduction of therapeutic interventions such as gastrointestinal decontamination and methanol metabolism inhibition, the correction of metabolic disturbances, and the establishment of novel diagnostic/screening nanoparticle-based strategies for methanol poisoning such as the discovery of ADH inhibitors as well as the detection of the adulteration of alcoholic drinks by nanoparticles in order to prevent methanol poisoning. In conclusion, increasing warnings and knowledge about clinical manifestations, medical interventions, and novel strategies for methanol poisoning probably results in a decrease in the death load.

Hydrogen production from hazardous petroleum sludge gasification over nickel-loaded porous ZSM-5 and Al2O3 catalysts under air condition

In this study, the potential of petroleum sludge (PS) for hydrogen production via the gasification process was evaluated. For this purpose, nickel (Ni)-loaded ZSM-5 and γ-Al₂O₃ (Ni-ZS and Ni-Al) catalysts were prepared and employed for PS gasification in air condition. The effects of different supports, Ni loading content, and reaction temperatures on the production of hydrogen-rich syngas along with the stability and reusability of the best catalyst were investigated. Applying 5%Ni-ZS obtained more gas yield (68.09 wt%) and hydrogen selectivity (25.04 vol%) compared to those obtained by 5%Ni-Al mostly owing to weak metal-support interactions which led to the dominance of well-dispersed metallic Ni. At various Ni loading percentages, 10%Ni-ZS showed the highest catalytic efficiency, which increased both gas yield (70.92 wt%) and hydrogen selectivity (30.74 vol%). However, excessive Ni content (especially 20%) significantly reduced the gas yield and hydrogen selectivity because of limited accessibility of support's active sites, poor dispersion of Ni, and inappropriate acidity. Increasing the temperature promoted the gas yield and produced hydrogen, where the highest gas yield (73.18 wt%) and hydrogen selectivity (33.15 vol%) were obtained at 850 °C due to the endothermic nature of gasification reactions. The 10%Ni-ZS catalyst showed proper stability during three consecutive experiments at 850 °C. The spent catalyst was successfully regenerated without a significant reduction in activity or selectivity.

Thermocatalytic conversion of wood-plastic composite over HZSM-5 catalysts

Air gasification of the Wood-Plastic Composite (WPC) was performed over Ni-loaded HZSM-5 catalysts to generate H₂-rich gas. Increasing SiO₂/Al₂O₃ ratio (SAR) of HZSM-5 adversely affected catalytic activity, where the highest gas yield (51.38 wt%) and H₂ selectivity (27.01 vol%) were acquired using 20 %Ni/HZSM-5(30) than those produced over 20 %Ni/HZSM-5(80) and 20 %Ni/HZSM-5(280). Reducing SAR was also favorably conducive to increasing the acyclic at the expense of cyclic compounds in oil products. These phenomena are attributed to enhanced acid strength and Ni dispersion of 20 %Ni/HZSM-5(30) catalyst. Moreover, catalytic activity in the terms of gas yield and H₂ selectivity enhanced with growing Ni loading to 20 %. Also, the addition of promoters (Cu and Ca) to 20 %Ni/HZSM-5(30) boosted the catalytic efficiency for H₂-rich gas generation. Raising temperature indicated a positive relevance with the gas yield and H₂ selectivity. WPC valorization via gasification technology would be an outstanding outlook in the terms of a waste-to-energy platform.

H2 generation from steam gasification of swine manure over nickel-loaded perovskite oxides catalysts

In this study, nickel-loaded perovskite oxides catalysts were synthesized via the impregnation of 10%Ni on XTiO₃ (X = Ce, Sr, La, Ba, Ca, and Fe) supports and employed in the catalytic steam gasification of swine manure to produce H₂-rich syngas for the first time. The synthesized catalysts were characterized using BET, H₂-TPR, XRD, HR-TEM, and EDX analysis. Briefly, using perovskite supports resulted in the production of ultrafine catalyst nanoparticles with a uniform dispersion of Ni particles. According to the catalytic activity test, the gas yield showed the increment as 10% Ni/LaTiO₃ < 10% Ni/FeTiO₃ < 10% Ni/CeTiO₃ < 10% Ni/BaTiO₃ < 10% Ni/SrTiO₃ < 10% Ni/CaTiO₃. Meanwhile, zero coke formation was achieved due to the oxygen mobility of prepared catalysts. Also, the increase in the H₂ production for the applied catalysts was in the sequence as 10% Ni/CeTiO₃ < 10% Ni/FeTiO₃ < 10% Ni/LaTiO₃ < 10% Ni/BaTiO₃ < 10% Ni/SrTiO₃ < 10% Ni/CaTiO₃. The maximum H₂ selectivity (∼48 vol%) obtained by10% Ni/CaTiO₃ was probably due to the synergistic effect of Ni and Ti on enhancing the water-gas shift reaction, and Ca on creating the maximum oxygen mobility compared to other alkaline earth metals doped at the A place of perovskite. Overall, this study provides a suitable solution for enhanced H₂ production through steam gasification of swine manure along with suggesting the appropriate supports to prevent Ni deactivation by lowering coke formation at the same time.

Economic and Environmental Performance of an Integrated CO2 Refinery

The consequences of global warming call for a shift to circular manufacturing practices. In this context, carbon capture and utilization (CCU) has become a promising alternative toward a low-emitting chemical sector. This study addresses for the first time the design of an integrated CO₂ refinery and compares it against the business-as-usual (BAU) counterpart. The refinery, which utilizes atmospheric CO₂, comprises three synthesis steps and coproduces liquefied petroleum gas, olefins, aromatics, and methanol using technologies that were so far studied decoupled from each other, hence omitting their potential synergies. Our integrated assessment also considers two residual gas utilization (RGU) designs to enhance the refinery's efficiency. Our analysis shows that a centralized cluster with an Allam cycle for RGU can drastically reduce the global warming impact relative to the BAU (by ≈135%) while simultaneously improving impacts on human health, ecosystems, and resources, thereby avoiding burden-shifting toward human health previously observed in some CCU routes. These benefits emerge from (i) recycling CO₂ from the cycle, amounting to 11.2% of the total feedstock, thus requiring less capture capacity, and (ii) reducing the electricity use while increasing heating as a trade-off. The performance of the integrated refinery depends on the national grid, while its high cost relative to the BAU is due to the use of expensive electrolytic H₂ and atmospheric CO₂ feedstock. Overall, our work highlights the importance of integrating CCU technologies within chemical clusters to improve their economic and environmental performance further.

A computational investigation of the decomposition of acetic acid in H-SSZ-13 and its role in the initiation of the MTO process

The zeolite-catalyzed reaction of acetic acid is important in the direct utilization of biomass and also plays a role in the reactivity of oxygenates in the methanol-to-olefins (MTO) process.

Cr-Zn/Ni-Containing Nanocomposites as Effective Magnetically Recoverable Catalysts for CO2 Hydrogenation to Methanol: The Role of Metal Doping and Polymer Co-Support

CO2 hydrogenation to methanol is an important process that could solve the problem of emitted CO2 that contributes to environmental concern. Here we developed Cr-, Cr-Zn-, and Cr-Ni-containing nanocomposites based on a solid support (SiO2 or Al2O3) with embedded magnetic nanoparticles (NPs) and covered by a cross-linked pyridylphenylene polymer layer. The decomposition of Cr, Zn, and Ni precursors in the presence of supports containing magnetic oxide led to formation of amorphous metal oxides evenly distributed over the support-polymer space, together with the partial diffusion of metal species into magnetic NPs. We demonstrated the catalytic activity of Cr2O3 in the hydrogenation reaction of CO2 to methanol, which was further increased by 50% and 204% by incorporation of Ni and Zn species, respectively. The fine intermixing of metal species ensures an enhanced methanol productivity. Careful adjustment of constituent elements, e.g., catalytic metal, type of support, presence of magnetic NPs, and deposition of hydrophobic polymer layer contributes to the synergetic promotional effect required for activation of CO2 molecules as well. The results of catalytic recycle experiments revealed excellent stability of the catalysts due to protective role of hydrophobic polymer.

Valorization of biomass through gasification for green hydrogen generation: A comprehensive review

Green and sustainable hydrogen from biomass gasification processes is one of the promising ways to alternate fossil fuels-based hydrogen production. First off, an overview of green hydrogen generation from biomass gasification processes is presented and the corresponding possible gasification reactions and the effect of respective experimental criteria are explained in detail. In addition, a comprehensive explanation of the catalytic effect on tar reduction and hydrogen generation via catalytic gasification is presented regarding the functional mechanisms of various types of catalysts. Furthermore, the commercialization aspects, the associated technical challenges and barriers, and the prospects of a biomass gasification process for green hydrogen generation are discussed. Finally, this comprehensive review provides the related advancements, challenges, and great insight of biomass gasification for the green hydrogen generation to realize a sustainable hydrogen society via biomass valorization.

COx conversion to aromatics: a mini-review of nanoscale performance

The conversion of CO_x into value-added green aromatics is considered as a promising route to achieve the world's decarbonization due to its considerable thermodynamic driving force and atomic economy where low H/C ratio aromatics are chosen as a product. It is enabled by bifunctional nano-catalysts composed of metal oxides with abundant oxygen vacancies and acid zeolites, thus realizing superior selectivity in hydrocarbons at the single pass of CO_x conversion. In this mini-review, we mainly provide some thought-provoking insights at the nanoscale of this complicated process including the proximity of active sites, reaction mechanism, asymmetric desorption behavior of intermediates and final products and overall thermodynamic analysis. The facile surface diffusion of intermediates owing to the proximity of active sites stimulates the reaction, which follows an autocatalytic process. This positive feedback attributed to the autocatalytic cycle accelerates the transformation of energy and materials in the thermodynamically optimal direction, making the reaction highly selective towards the final products. This complicated coupling process, like a nano-maze constituted by these micro-environment factors, is complicated in terms of the reaction pathway but highly selective to a fixed direction guided by overall thermodynamics. Deep understanding of such an autocatalytic cycle at the nanoscale paves the way for the rational design of next-generation high-performance catalysts.

Advancing Critical Chemical Processes for a Sustainable Future: Challenges for Industry and the Max Planck–Cardiff Centre on the Fundamentals of Heterogeneous Catalysis (FUNCAT)

Catalysis is involved in around 85 % of manufacturing industry and contributes an estimated 25 % to the global domestic product, with the majority of the processes relying on heterogeneous catalysis. Despite the importance in different global segments, the fundamental understanding of heterogeneously catalysed processes lags substantially behind that achieved in other fields. The newly established Max Planck-Cardiff Centre on the Fundamentals of Heterogeneous Catalysis (FUNCAT) targets innovative concepts that could contribute to the scientific developments needed in the research field to achieve net zero greenhouse gas emissions in the chemical industries. This Viewpoint Article presents some of our research activities and visions on the current and future challenges of heterogeneous catalysis regarding green industry and the circular economy by focusing explicitly on critical processes. Namely, hydrogen production, ammonia synthesis, and carbon dioxide reduction, along with new aspects of acetylene chemistry.

Production of valuable chemicals through the catalytic pyrolysis of harmful oil sludge over metal-loaded HZSM-5 catalysts

This research studied the catalytic pyrolysis of oil sludge (OS) over metal-loaded HZSM-5 catalysts, an eco-friendly and cost-effective technology to produce value-added aromatics such as benzene, toluene, ethylbenzene, and xylene (BTEXs). In particular, it evaluated the respective effects of the experimental parameters: the type and amount of the metal loaded, the reaction temperature, and the OS/catalyst ratio, on the BTEXs yield sequentially to achieve optimum conditions. This evaluation showed that the highest yields of the BTEXs (6.61 wt%) and other aromatics were achieved when Ni was incorporated into the HZSM-5 (Ni/HZSM-5) followed by the corresponding yields of Ga/HZSM-5 and Fe/HZSM-5, due to a better distribution of Ni on the support surface and an enhanced acidity strength of this catalyst. Further, increase in Ni loading (up to 10 wt% Ni/HZSM-5) increased the BTEXs yield to 13.48 wt%. However, the excessive Ni loading (15 wt% Ni/HZSM-5) resulted in a reduced BTEXs yield due to the blockage of the zeolite channels. Next, an increase in the reaction temperature from 500 °C to 600 °C increased the yield of the BTEXs and other aromatics. However, a further increase in the reaction temperature to 650 °C decreased slightly their yield because of the stimulating secondary reactions at high temperatures. The increase of catalyst amount (OS/catalyst of 1/3) also maximized the BTEXs yield (30.50 wt%).

Controllable Orientation Growth of ZSM-5 for Methanol to Hydrocarbon Conversion: Cooperative Effects of Seed Induction and Medium pH Control

The growth orientation of ZSM-5 zeolites strongly affects product selectivity in methanol conversion reaction. Here, we proposed a versatile synthetic strategy by introducing seeds and controlling medium pH to achieve controllable orientation growth of ZSM-5. The systematic analysis of the crystallization process indicated that the introduction of seeds ensured successful crystallization in a quasi-neutral solution and the dissolution rate of seeds and aluminosilicate determined the growth orientation of ZSM-5. In the quasi-neutral solution, the slow dissolution of seeds and aluminosilicate enhanced growth advantages along the c axis. The ratio between the length of the c axis and b axis (L_c/L_b) of the obtained ZSM-5 at pH of 7 could reach 8.1, much higher than 1.8 obtained at pH of 11. No obvious impact of seed added amount on growth orientation was found, while with increasing seed crystal size, the obtained ZSM-5 showed preferred growth along the c axis. The L_c/L_b of the sample adding seeds with a size of 355 nm reached 7.9, much higher than 2.1 of the sample adding seeds with a size of 70 nm. The obtained ZSM-5 with specific growth orientation exhibited potential shape selectivity in methanol to aromatics and olefin reaction. This work opens new possibilities to tailor the orientation growth of ZSM-5 based on the seed-induced strategy under mild conditions.

Point mutations that boost aromatic amino acid production and CO2 assimilation in plants

Aromatic compounds having unusual stability provide high-value chemicals and considerable promise for carbon storage. Terrestrial plants can convert atmospheric CO₂ into diverse and abundant aromatic compounds. However, it is unclear how plants control the shikimate pathway that connects the photosynthetic carbon fixation with the biosynthesis of aromatic amino acids, the major precursors of plant aromatic natural products. This study identified suppressor of tyra2 (sota) mutations that deregulate the first step in the plant shikimate pathway by alleviating multiple effector-mediated feedback regulation in Arabidopsis thaliana. The sota mutant plants showed hyperaccumulation of aromatic amino acids accompanied by up to a 30% increase in net CO₂ assimilation. The identified mutations can be used to enhance plant-based, sustainable conversion of atmospheric CO₂ to high-energy and high-value aromatic compounds.

Highly Enhanced Aromatics Selectivity by Coupling of Chloromethane and Carbon Monoxide over H-ZSM-5

The transformation of methane into high value-added chemicals such as aromatics provides a more desired approach towards sustainable chemistry but remains a critical challenge due to the low selectivity of aromatics and poor stability. Herein, we first report a coupling reaction of CH₃ Cl and CO (CCTA) based on methane conversion, which achieves extremely high aromatics selectivity (82.2 %) with the selectivity of BTX up to ca. 60 % over HZSM-5. The promoting effects have been demonstrated on other zeolites especially 10-membered rings (10 MR) zeolites. Multiple characterizations show that 2,3-dimethyl-2-cyclopentene-1-one (DMCPO) is generated from acetyl groups and olefins. Furthermore, isotopic labeling analysis confirms that CO is inserted into the DMCPO and aromatics rings. A new aromatization mechanism is proposed, including the formation of the above intermediates, which conspicuously weakens the hydrogen transfer reaction, leading to a considerable increase of aromatics selectivity and a dramatic drop in alkanes.

Catalyst sites and active species in the early stages of MTO conversion over cobalt AlPO-18 followed by IR spectroscopy

Reaction-time resolved IR spectroscopy highlights the role of CO and surface –OCH3 in the MTO conversion catalysed by CoAPO-18 with maximised concentration of acidic sites.

High value utilization of biomass: selective catalytic transformation of lignocellulose into bio-based 2,5-dimethylphenol

A new strategy for the synthesis of high-value biochemical 2,5-dimethylphenol was constructed by lignocellulose catalytic pyrolysis and selective hydroxylation.