C2 Oxygenates Research Articles

The Significant Differences in Solvation Thermodynamics of C1–C3 Oxygenates in Hydrophilic versus Hydrophobic Pores of a Hydrophilic Ti-FAU Zeolite Model

The Significant Differences in Solvation Thermodynamics of C1–C3 Oxygenates in Hydrophilic versus Hydrophobic Pores of a Hydrophilic Ti-FAU Zeolite Model

Direct Oxidation of Methane to C1 Oxygenates on Cu/ZSM‐5: Reaction Property and Configuration of Cu Species

AbstractDirect oxidation of methane (DOM) under mild conditions is arguably one of the holy grails in chemistry. Cu‐based zeolite catalysts have attracted much attention for their high yield and selectivity of C1 oxygenates. However, the structure‐activity relationships of DOM remain controversial due to the complex configurations of Cu on zeolites. Herein, we prepared Cu/ZSM‐5 catalysts with various Cu loading and investigated the effects of Cu configurations on the DOM reaction. By combining the characterization techniques and evaluating the catalytic performance, we found that the configurations of Cu species could significantly affect the yield and distribution of C1 oxygenates, which was strongly dependent on Cu loading. The highly dispersed mononuclear CuII in the channels of ZSM‐5 is proved to be highly active. While the multinuclear Cu species inhibit the formation of HCOOH, simultaneously suppressing the overall reaction yield. The agglomerated CuO species on the surface of ZSM‐5 show a relatively low correlation with DOM reaction. Thus, the relationship between the yield of C1 oxygenates and Cu loading exhibits a typical volcanic curve and 2.2 wt.% Cu/ZSM‐5 possess the best performance using H2O2 as oxidant (productivity of 17,000 μmol gcat−1 h−1 with 98.6 % selectivity at 50 °C).

In Situ Surfaced Mn-Mn Dimeric Sites Dictate CO Hydrogenation Activity and C2 Selectivity over MnRh Binary Catalysts.

Massive ethanol production has long been a dream of human society. Despite extensive research in past decades, only a few systems have the potential of industrialization: specifically, Mn-promoted Rh (MnRh) binary heterogeneous catalysts were shown to achieve up to 60% C2 oxygenates selectivity in converting syngas (CO/H2) to ethanol. However, the active site of the binary system has remained poorly characterized. Here, large-scale machine-learning global optimization is utilized to identify the most stable Mn phases on Rh metal surfaces under reaction conditions by exploring millions of likely structures. We demonstrate that Mn prefers the subsurface sites of Rh metal surfaces and is able to emerge onto the surface forming MnRh surface alloy once the oxidative O/OH adsorbates are present. Our machine-learning-based transition state exploration further helps to resolve automatedly the whole reaction network, including 74 elementary reactions on various MnRh surface sites, and reveals that the Mn-Mn dimeric site at the monatomic step edge is the true active site for C2 oxygenate formation. The turnover frequency of the C2 product on the Mn-Mn dimeric site at MnRh steps is at least 107 higher than that on pure Rh steps from our microkinetic simulations, with the selectivity to the C2 product being 52% at 523 K. Our results demonstrate the key catalytic role of Mn-Mn dimeric sites in allowing C-O bond cleavage and facilitating the hydrogenation of O-terminating C2 intermediates, and rule out Rh metal by itself as the active site for CO hydrogenation to C2 oxygenates.

Atomically Dispersed Iron‐Copper Dual‐Metal Sites Synergistically Boost Carbonylation of Methane

AbstractThe direct liquid‐phase oxidative carbonylation of methane, utilizing abundant natural gas, offers a mild and straightforward alternative. However, most catalysts proposed for this process suffer from low acetic acid yields due to few active sites and rapid C1 oxygenate generation, impeding their industrial feasibility. Herein, we report a highly efficient 0.1Cu/Fe‐HZSM‐5‐TF (TF denotes template‐free synthesis) catalyst featuring exclusively mononuclear Fe and Cu anchored in the ZSM‐5 channels. Under optimized conditions, the catalyst achieved an unprecedented acetic acid yield of 40.5 mmol gcat−1 h−1 at 50 °C, tripling the previous records of 12.0 mmol gcat−1 h−1. Comprehensive characterization, isotope‐labeled experiments and density functional theory (DFT) calculations reveal that the homogeneous mononuclear Fe sites are responsible for the activation and oxidation of methane, while the neighboring Cu sites play a key role in retarding the oxidation process, promoting C−C coupling for effective acetic acid synthesis. Furthermore, the methyl‐group carbon in acetic acid originates solely from methane, while its carbonyl‐group carbon is derived exclusively from CO, rather than the conversion of other C1 oxygenates. The proposed bimetallic catalyst design not only overcomes the limitations of current catalysts but also generalizes the oxidative carbonylation of other alkanes, demonstrating promising advancements in sustainable chemical synthesis.

Atomically Dispersed Iron-Copper Dual-Metal Sites Synergistically Boost Carbonylation of Methane.

The direct liquid-phase oxidative carbonylation of methane, utilizing abundant natural gas, offers a mild and straightforward alternative. However, most catalysts proposed for this process suffer from low acetic acid yields due to few active sites and rapid C1 oxygenate generation, impeding their industrial feasibility. Herein, we report a highly efficient 0.1Cu/Fe-HZSM-5-TF (TF denotes template-free synthesis) catalyst featuring exclusively mononuclear Fe and Cu anchored in the ZSM-5 channels. Under optimized conditions, the catalyst achieved an unprecedented acetic acid yield of 40.5 mmol gcat -1 h-1 at 50 °C, tripling the previous records of 12.0 mmol gcat -1 h-1. Comprehensive characterization, isotope-labeled experiments and density functional theory (DFT) calculations reveal that the homogeneous mononuclear Fe sites are responsible for the activation and oxidation of methane, while the neighboring Cu sites play a key role in retarding the oxidation process, promoting C-C coupling for effective acetic acid synthesis. Furthermore, the methyl-group carbon in acetic acid originates solely from methane, while its carbonyl-group carbon is derived exclusively from CO, rather than the conversion of other C1 oxygenates. The proposed bimetallic catalyst design not only overcomes the limitations of current catalysts but also generalizes the oxidative carbonylation of other alkanes, demonstrating promising advancements in sustainable chemical synthesis.

Photocatalytic Conversion of Methane to Ethanol at a Three-Phase Interface with Concentration-Matched Hydroxyl and Methyl Radicals.

The direct oxidation of CH4 to C2H5OH is attractive but challenging owing to the intricate processes involving carbon-chain growth and hydroxylation simultaneously. The inherent difficulty arises from the strong tendency of CH4 to overoxidize in the commonly used pressurized powder suspension systems rich in reactive oxygen radicals (ROR), which are specifically designed for CH4 concentration and activation. Meanwhile, the strong tendency of nucleophilic attack of potent ROR on the C-C bond of the resulting product C2H5OH ultimately leads to a higher selectivity for C1 oxygenates. This study addresses this multifaceted issue by designing a three-phase interface based on a hydrophilic floating Fe(III)-cross-linked macroporous alginate hydrogel film encapsulated with C3N4 [Fe(III)@ACN] to simultaneously enhance the accessibility of H2O and CH4 molecules to the active sites and species within the macroporous channel. The hydrophilic properties of Fe(III)@ACN allow the in situ production of H2O2 from C3N4 through the water oxidation reaction under irradiation. The concurrent photoinduced Fe(II) triggers Fenton reaction with H2O2 to produce •OH. The enhanced mass transfer of CH4 at the three-phase interface ensures the efficient formation of •CH3 by reacting with •OH, ultimately facilitating carbon-chain growth in the conversion pathway from CH4 to CH3OH and finally to C2H5OH with •CH3 and •OH present in comparable concentrations. Thus, the Fe(III)@ACN catalyst exhibits a remarkable 96% selectivity for alcohol, achieving a 90% selectivity for C2H5OH in the alcohol products. The C2H5OH production rate reaches 171.7 μmol g-1 h-1 without the need for precious-metal additive.

Density functional theory study of Cu based catalysts with sulfur modification for the selective conversion of syngas to C2 oxygenates

Low-cost catalysts based on Cu have emerged as promising catalysts for synthesizing ethanol from syngas, despite their limited selectivity to ethanol. This study investigates sulfur-modified Cu(100) surface for converting syngas to C2 oxygenates, and explores the intricate mechanism of C2 oxygenates formation from CO hydrogenation using density functional theory (DFT) calculations. The findings indicate that the CH2 and CH3 are the most advantageous monomers over other CHx (x = 1–3) intermediates, surpassing methanol and methane formation. This result significantly differs from observations on the Cu(100) surface. For C2 oxygenates formation, the most effective pathway involves the insertion of CHO into CH3 or CHO via C–C to generate a stable intermediate CH3CHO and OHCCHO on the S-Cu(100) surface. Additionally, the examination of electrical and structural characteristics reveals a mild charge transfer between Cu and S, which enhances the catalytic performance for syngas to C2 oxygenates. Therefore, this work provides valuable insights into the role of sulfur-modified Cu(100) surface in enhancing the selectivity to C2 oxygenates.

The photoionization of methoxymethanol: Fingerprinting a reactive C2 oxygenate in a complex reactive mixture.

Methoxymethanol (CH3OCH2OH) is a reactive C2 ether-alcohol that is formed by coupling events in both heterogeneous and homogeneous systems. It is found in complex reactive environments-for example those associated with catalytic reactors, combustion systems, and liquid-phase mixtures of oxygenates. Using tunable synchrotron-generated vacuum-ultraviolet photons between 10.0 and 11.5eV, we report on the photoionization spectroscopy of methoxymethanol. We determine that the lowest-energy photoionization process is the dissociative ionization of methoxymethanol via H-atom loss to produce [C2H5O2]+, a fragment cation with a mass-to-charge ratio (m/z) = 61.029. We measure the appearance energy of this fragment ion to be 10.24 ± 0.05eV. The parent cation is not detected in the energy range examined. To elucidate the origin of the m/z = 61.029 (C2H5O2) fragment, we used automated electronic structure calculations to identify key stationary points on the cation potential energy surface and compute conformer-specific microcanonical rate coefficients for the important unimolecular processes. The calculated H-atom dissociation pathway results in a [C2H5O2]+ fragment appearance at 10.21eV, in excellent agreement with experimental results.

Phase engineering of Fe2O3 nanocrystals for the direct oxidation of CH4 to HCOOH

The direct oxidation of methane (CH4) under mild conditions is a highly desirable technology to achieve the low-carbon and atom-economic production of high-value-added C1 oxygenates. However, the difficult activation of the CH bond of CH4 and the overoxidation of C1 oxygenates to carbon dioxide (CO2) are still the major bottlenecks. Herein, we systematically investigate the phase engineering of Fe2O3 in dependence on the performance of the direct oxidation of CH4. The cubic phase of Fe2O3 (Fe2O3-c) nanocrystals enables the direct oxidation of CH4 to HCOOH (DOMF) under mild aqueous conditions, and the HCOOH yield and selectivity could reach 6.315 mmol gcat−1 h−1 and 89.4%, which are 69.3 and 1.34 times higher than those of the hexagonal phase of Fe2O3 (Fe2O3-h) nanocrystals. Mechanism experiments indicate that Fe2O3-c nanocrystals can optimal CH4 adsorption behavior, favoring to the occurrence of the DOMF. In addition, in situ DRIFTS demonstrates that the DOMF is the radical reaction process that the activation of CH bond is caused by the ·OH radical. Subsequently, the unstable CH3OOH and stable CH3OH intermediates undergo further oxidation to form HCOOH. This work offers the phase engineering strategy to enhance the catalytic performance and reveal the reaction mechanism for the direct oxidation of CH4.

Tailored Exfoliation of Polymeric Carbon Nitride for Photocatalytic H2O2 Production and CH4 Valorization Mediated by O2 Activation

AbstractThe exfoliation of bulk C3N4 (BCN) into ultrathin layered structure is an effective strategy to boost photocatalytic efficiency by exposing interior active sites and accelerating charge separation and transportation. Herein, we report a novel nitrate anion intercalation‐decomposition (NID) strategy that is effective in peeling off BCN into few‐layer C3N4 (fl‐CN) with tailored thickness down to bi‐layer. This strategy only involves hydrothermal treatment of BCN in diluted HNO3 aqueous solution, followed by pyrolysis at various temperatures. The decomposition of the nitrate anions not only exfoliates BCN and changes the band structure, but also incorporates oxygen species onto fl‐CN, which is conducive to O2 adsorption and hence relevant chemical processes. In photocatalytic O2 reduction under visible light irradiation, the H2O2 production rate over the optimal fl‐CN‐530 catalyst is 952 μmol g−1 h−1, which is 8.8 times that over BCN. More importantly, under full arc irradiation and in the absence of hole scavenger, CH4 can be photocatalytically oxidized by on‐site formed H2O2 and active oxygen species to generate value‐added C1 oxygenates with high selectivity of 99.2 % and record‐high production rate of 1893 μmol g−1 h−1 among the metal‐free C3N4‐based photocatalysts.

Tailored Exfoliation of Polymeric Carbon Nitride for Photocatalytic H2O2 Production and CH4 Valorization Mediated by O2 Activation.

The exfoliation of bulk C3N4 (BCN) into ultrathin layered structure is an effective strategy to boost photocatalytic efficiency by exposing interior active sites and accelerating charge separation and transportation. Herein, we report a novel nitrate anion intercalation-decomposition (NID) strategy that is effective in peeling off BCN into few-layer C3N4 (fl-CN) with tailored thickness down to bi-layer. This strategy only involves hydrothermal treatment of BCN in diluted HNO3 aqueous solution, followed by pyrolysis at various temperatures. The decomposition of the nitrate anions not only exfoliates BCN and changes the band structure, but also incorporates oxygen species onto fl-CN, which is conducive to O2 adsorption and hence relevant chemical processes. In photocatalytic O2 reduction under visible light irradiation, the H2O2 production rate over the optimal fl-CN-530 catalyst is 952 μmol g-1 h-1, which is 8.8 times that over BCN. More importantly, under full arc irradiation and in the absence of hole scavenger, CH4 can be photocatalytically oxidized by on-site formed H2O2 and active oxygen species to generate value-added C1 oxygenates with high selectivity of 99.2 % and record-high production rate of 1893 μmol g-1 h-1 among the metal-free C3N4-based photocatalysts.

Electrochemical Reduction of CO2: A Common Acetyl Path to Ethylene, Ethanol or Acetate

Ethylene is well known as the primary product of CO2 reduction at Cu electrocatalysts using zero-gap membrane electrode assembly cells with gas diffusion cathodes. Other types of Cu electrocatalysts including oxide-derived Cu, CuSn and CuSe yield relatively more C2 oxygenates; however, the mechanisms for C2 product selectivity are not well established. This work considers selectivity trends of Cu-P0.065, Cu-Sn0.03, and Cu2Se electrocatalysts made using a standard one pot synthesis method. Results show that Cu-P0.065 electrocatalysts (Cu δ+ = 0.13) retain ethylene as a primary product with relatively higher Faradaic efficiencies (FE = 43% at 350 mA cm−2) than undoped Cu electrocatalysts (FE = 31% at 350 mA cm−2) at the same current density. The primary CO2 reduction product at Cu-Sn0.03 (Cu δ+ = 0.27) electrocatalysts shifts to ethanol (FE = 48% at 350 mA cm−2) while CO2 reduction at Cu2Se (Cu δ+ = 0.47) electrocatalysts favor acetate production (FE = 40% at 350 mA cm−2). Based on these results, we propose a common acetyl intermediate and a mechanism for selective formation of ethylene, ethanol or acetate based on the degree of partial positive charge (δ + ) of Cu reaction sites.

TiO2 nanofiber-supported copper nanoparticle catalysts for highly efficient methane conversion to C1 oxygenates under mild conditions

TiO2 nanofiber-supported copper nanoparticle catalysts for highly efficient methane conversion to C1 oxygenates under mild conditions

Selective photocatalytic oxidation of methane to C1 oxygenates by regulating sizes and facets over Au/ZnO

Selective photocatalytic oxidation of methane to C1 oxygenates by regulating sizes and facets over Au/ZnO

Surface hydrophobic MIL-100(Fe) MOFs to boost methane oxidation with nearly total selectivity to C1 oxygenates under mild conditions

Direct methane conversion into value-added liquid oxygenates is a holy-grail reaction. We modified MIL-100(Fe) MOFs materials with highly dispersed hydrophobic polydimethysiloxane nanoparticles to significantly enhance their water resistance. The C1 oxygenates demonstrated an impressive yield and selectivity of 83.13 mmol g cat.−1h−1 and 100 %, respectively, while achieving a turnover frequency of 332.5 h−1 for oxygenates. The results of spectroscopy characterization and theoretical calculation demonstrate that, during the hydrophobic modification process of the catalyst surface, the loss of some ligands leads to the formation of coordination unsaturated active sites (Fe(II) CUS). The Fe(II) CUS active sites can efficiently catalyze the cleavage of H2O2 to produce Fe(IV) = O active species with high Lewis acidity, those promote homolytic dissociation of methane C-H bond with a low energy barrier. This study expands the application of hydrophilic MOFs materials with coordinatively unsaturated metal sites in the heterogeneous catalytic reactions of liquid phase.

Bimetallic-Derived Catalytic Structures for CO2-Assisted Ethane Activation.

ConspectusIn recent years, the simultaneous upgrading of CO2 and ethane has emerged as a promising approach for generating valuable gaseous (CO, H2, and ethylene) and liquid (aromatics and C3 oxygenates) chemicals from the greenhouse gas CO2 and large-reserved shale gas. The key challenges for controlling product selectivity lie in the selective C-H and C-C bond cleavage of ethane with the assistance of CO2. Bimetallic-derived catalysts likely undergo alloying or oxygen-induced segregation under reaction conditions, thus providing diverse types of interfacial sites, e.g., metal/support (M/M'Ox) interface and metal oxide/metal (M'Ox/M) inverse interface, that are beneficial for selective CO2-assisted ethane upgrading. The alloying extent can be initially predicted by cohesive energy and atomic radius (or Wigner-Seitz radius), while the preference for segregation to form the on-top suboxide can be approximated using the work function, electronegativity, and binding strength of adsorbed oxygen. Furthermore, bimetallic-derived catalysts are typically supported on high surface area oxides. Modifying the reducibility and acidity/basicity of the oxide supports and introducing surface defects facilitate CO2 activation and oxygen supplies for ethane activation.Using in situ synchrotron characterization and density functional theory (DFT) calculations, we found that the electronic properties of oxygen species influence the selective cleavage of C-H/C-C bonds in ethane, with electron-deficient oxygen over the metal (or alloy) surface promoting nonselective bond scission to produce syngas and electron-enriched oxygen over the metal oxide/metal interface enhancing selective C-H scission to yield ethylene. We further demonstrate that the preferred structures of the catalyst surfaces, either alloy surfaces or metal oxide/metal inverse interfaces, can be controlled through the appropriate choice of metal combinations and their atomic ratios. Through a comprehensive comparison of experimental results and DFT calculations, the selectivity of C-C/C-H bond scission is correlated with the thermodynamically favorable bimetallic-derived structures (i.e., alloy surfaces or metal oxide/metal inverse interfaces) under reaction conditions over a wide range of bimetallic catalysts. These findings not only offer structural and mechanistic insights into bimetallic-derived catalysts but also provide design principles for selective catalysts for CO2-assisted activation of ethane and other light alkanes. This Account concludes by discussing challenges and opportunities in designing advanced bimetallic-derived catalysts, incorporating new reaction chemistries for other products, employing precise synthesis strategies for well-defined structures with optimized site densities, and leveraging time/spatial/energy-resolved in situ spectroscopy/scattering/microscopy techniques for comprehensive structural analysis. The research methodologies established here are helpful for the investigation of dynamic alloy and interfacial structures and should inspire more efforts toward the simultaneous upgrading of CO2 and shale gas.

2D h-BN material covered Cu confined catalysts: unraveling the function of spatial dimension in tuning activity and selectivity of syngas-to-C2 oxygenates

Improving catalytic performance of syngas conversion to form C2 oxygenates on the Cu-based catalyst is still a challenge. Here, 2D h-BN material covered Cu confined catalysts (xh-BN/Cu) with different spatial dimensions are rationally designed to unravel the function of spatial dimension in tuning the activity and selectivity of C2 oxygenates. The results show that the spatial dimension caused by h-BN coating in the h-BN/Cu catalyst can alter the dominant existence form of CHx(x=1-3) monomer and the corresponding activity and selectivity, in which the confinement effect arisen from h-BN coating with different spatial dimensions is confirmed to be the determined factor instead of the electronic effect. The screened 4.0h-BN/Cu catalyst has outstanding catalytic performance toward the production of dominant CHx(x=1-3) monomer and C2 oxygenates. The finding provides the new design principle to rationally construct 2D material covered metal confined catalysts by adjusting the confined spatial dimension to improve catalytic performance.

Surface modification of Fe5C2 by binding silica-based ligand: A theoretical explanation of enhanced C2 oxygenate selectivity

Elucidating the role(s) of support-like ligands remains a challenge in catalytic reaction like the Fischer-Tropsch Synthesis (FTS) catalyzed by the iron catalyst supported on silica. We herein theoretically investigated surface modification of Fe5C2 by silica-based ligand and its influence on C2 oxygenate selectivity in FTS, by carrying out DFT calculations on dissociation of CO and formations of CH4 and C2 on ha-SiO2/Fe5C2(510). To mimic the structure of surface modification, the ha-SiO2/Fe5C2(510) model was built up by binding the silica cluster (the ha-SiO2 ligand) to Fe5C2(510). DFT calculations elucidated that the C + CH coupling with the lowest activation barrier among all the possible routes of C2 formation on Fe5C2(510) is suppressed after modification with the ha-SiO2 ligand because the binding ha-SiO2 ligand limits the geometry relaxation caused by the C+CH coupling. However, CO molecule is anchored by the ha-SiO2 ligand via hydrogen bond, suppressing the CO cleavage because the d-valence band center of Fe5C2(510) lowers in energy by surface modification with the ha-SiO2 ligand, but facilitating the C + CO coupling with the lowest activation barrier among all the possible routes of C2 formation. Also, CH4 formation in the ha-SiO2/Fe5C2(510) case is not so easy as that on Fe5C2(510). Therefore, C2 oxygenate is formed more easily in the ha-SiO2/Fe5C2(510) case than in the Fe5C2(510) case. The result agrees with the experimental observation that C2 oxygenate selectivity became high for iron-based FTS catalyst after surface modification of by silica-based ligand.

Design of catalyst for syngas conversion to C2 oxygenates via confining diatomic metal within the framework of 2D carbon-based materials

The selectivity of syngas-to-C2 oxygenates still faces a big challenge. In the present study, the different 2D carbon-based substrates (g-C3N4, GDY and C2N) supported diatomic RhCo catalysts are constructed reasonably to enhance C2 oxygenates selectivity. The complicated reaction network is studied by means of DFT calculations; the influences of the species coverage, the reaction temperature and pressure are examined using microkinetic modeling. The results indicate that RhCo/g-C3N4, RhCo/GDY and RhCo/C2N catalysts have excellent structural stability. The preferred existence form of CHx(x = 1–3) monomer, as well as the activity and selectivity of CHx monomer and C2 oxygenates generation are strongly related to the coordination environment of 2D carbon-based material supported diatomic RhCo catalysts. The screened RhCo/g-C3N4 catalyst could perform the outstanding catalytic performance toward the generation of C2 oxygenates CH2CO and CH3CO, in which the coordination environment of g-C3N4 makes the diatomic RhCo cluster lose more electron and d-band center far away from Fermi level. This work provides an alternative way to construct 2D substrate supported diatomic metal catalysts in syngas-to-C2 oxygenates, adjusting 2D substrate type could change the local coordination environment of diatomic metal sites and further improve catalytic performance.

Efficient catalysts of surface hydrophobic Cu-BTC with coordinatively unsaturated Cu(I) sites for the direct oxidation of methane

Selective oxidation of methane to organic oxygenates over metal-organic frameworks (MOFs) catalysts at low temperature is a challenging topic in the field of C1 chemistry because of the inferior stability of MOFs. Modifying the surface of Cu-BTC via hydrophobic polydimethylsiloxane (PDMS) at 235 °C under vacuum not only can dramatically improve its catalytic cycle stability in a liquid phase but also generate coordinatively unsaturated Cu(I) sites, which significantly enhances the catalytic activity of Cu-BTC catalyst. The results of spectroscopy characterizations and theoretical calculation proved that the coordinatively unsaturated Cu(I) sites made H2O2 dissociative into •OH, which formed Cu(II)-O active species by combining with coordinatively unsaturated Cu(I) sites for activating the C-H bond of methane. The high productivity of C1 oxygenates (CH3OH and CH3OOH) of 10.67 mmol gcat.-1h-1 with super high selectivity of 99.6% to C1 oxygenates was achieved over Cu-BTC-P-235 catalyst, and the catalyst possessed excellent reusability.