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Benzoxazine-based polymer (PBZ) acts as a catalyst for converting CO2 into cyclic carbonates. PBZ-ODA was successfully synthesized and examined for its catalytic efficiency, proving to be effective under milder conditions with higher yields at room temperature without solvents. Various terminal monoepoxides showed good to excellent conversion rates, while epoxides with aromatic or bulky groups and second oxirane rings also were able to produce corresponding cyclic carbonates. Recyclability tests demonstrated that regenerated PBZ-ODA retained 93% of its catalytic activity. Overall, there was a low catalyst deactivation, as investigated by chemical experiments, SEM-EDX, TGA, FT-IR, XPS, XRD and NMR. The catalyst is reusable and suitable for use in flow or batch reactors. [ABSTRACT FROM AUTHOR]

In this research, a one-dimensional heterogeneous model is developed to simulate the partial oxidation of methanol to formaldehyde over a molybdenum-iron catalyst in an industrial isothermal reactor at dynamic condition. The considered isothermal reactor is modelled based on the mass and energy balance equations considering catalyst deactivation. Based on the simulation results, decline in the catalyst activity from 1.0 to 0.73 decreases the rate of formaldehyde production rate from 94.9 kmol h−1 to 89.63 kmol h−1 during process run time. Subsequently, a multi-objective optimization problem is programmed to enhance formaldehyde productivity and minimize the production decline during process run time. To select the effective decision variables, a sensitivity analysis is performed based on the developed dynamic model. Then, the programmed multi-objective optimization problem is replaced with a single objective by the weighted sum method, and the problem is handled by the genetic algorithm method to determine the optimal trajectory of coolant temperature. The simulation results showed that the average formaldehyde production rate increases from 92.11 kmol h−1 to 95.22 kmol h−1 when the optimal conditions are applied to the reactor. [ABSTRACT FROM AUTHOR]

Copyright of Petroleum Refinery Engineering is the property of Petroleum Refinery Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The purpose of this work was to establish a process model of a vacuum gas oil industrial hydrocracking. In this model, we divide the lumps by 10 K as the interval, the reaction kinetics model is established based on discrete lumping method. Besides, a relevant catalyst deactivation function for catalyst activity calculation was proposed, which includes the flow and properties of the feed for a long period. The simulated hydrocracking unit is the process with hydrotreating and hydrocracking reactors in series. Therefore, it is necessary to build a hydrotreating model to represent the feed oil properties at the inlet of the hydrocracking reactor. Owing to absence industrial hydrotreating reactor monitor data, the hydrotreating model is established by using the data of the pilot plant loaded with the same catalyst. The hydrocracking reactor model is established through the material balance, heat balance, and momentum balance equations. Multiple sets of data are used to verify the established hydrocracking reactor model, the errors between the calculated value and the actual value of hydrocracking products are basically less than 10 %, and the relative errors of the predicted temperature and pressure are less than 0.5 %. Based on the catalyst deactivation function, the average relative errors of the model can be reduced by 50%. The variation of the reactor along the height is analyzed, and the result shows that the model accuracy simulated the target hydrocracking unit. [ABSTRACT FROM AUTHOR]

Increased levels and detrimental effects of volatile organic compounds (VOCs) on air quality and human health have become an important issue in the environmental field. Benzene is classified as one of the most hazardous air pollutants among non-halogenated aromatic hydrocarbons with toxic, carcinogenic, and mutagenic effects. Various technologies have been applied to decrease harmful emissions from various sources such as petrochemistry, steel manufacturing, organic chemical, paint, adhesive, and pharmaceutical production, vehicle exhausts, etc. Catalytic oxidation to CO2 and water is an attractive approach to VOC removal due to high efficiency, low energy consumption, and the absence of secondary pollution. However, catalytic oxidation of the benzene molecule is a great challenge because of the extraordinary stability of its six-membered ring structure. Developing highly efficient catalysts is of primary importance for effective elimination of benzene at low temperatures. This review aims to summarize and discuss some recent advances in catalyst composition and preparation strategies. Advantages and disadvantages of using noble metal-based catalysts and transition metal oxide-based catalysts are addressed. Effects of some crucial factors such as catalyst support nature, metal particle size, electronic state of active metal, redox properties, reactivity of lattice oxygen and surface adsorbed oxygen on benzene removal are explored. Thorough elucidation of reaction mechanisms in benzene oxidation is a prerequisite to develop efficient catalysts. Benzene oxidation mechanisms are analyzed based on in situ catalyst characterization, reaction kinetics, and theoretical simulation calculations. Considering the role of oxygen vacancies in improving catalytic performance, attention is given to oxygen defect engineering. Catalyst deactivation due to coexistence of water vapor and other pollutants, e.g., sulfur compounds, is discussed. Future research directions for rational design of catalysts for complete benzene oxidation are provided. [ABSTRACT FROM AUTHOR]

A mechanism for carbon deposition and its impact on the reaction kinetics of Methane Dry Reforming (MDR) using Rhodium‐based catalysts is presented. By integrating Raman spectroscopy with kinetic analysis in an operando‐annular chemical reactor under strict chemical conditions, we discovered that carbon deposition on a Rh/α‐Al2O3 catalyst follows a nucleation‐growth mechanism. The dynamics of carbon aggregates at the surface is found to be ruled by the CO2/CH4 ratio and the inlet CH4 concentration. The findings elucidate the spatiotemporal development of carbon aggregates on the catalyst surface and their effects on catalytic performance. Furthermore, the proposed mechanism for carbon formation shows that the influence of CO2 on MDR kinetics is an indirect result of carbon accumulation over time frames exceeding the turnover frequency, thus reconciling conflicting reports in the literature regarding CO2′s kinetic role in MDR. [ABSTRACT FROM AUTHOR]

Stability is crucial for the practical application of heterogeneous catalysts, particularly in industrial processes, where catalyst deactivation often occurs due to factors such as sintering, poisoning, and active site degradation. This study investigates the effectiveness of utilizing covalent organic frameworks (COFs), specifically RT‐COF‐1, to enhance the stability of Cu/Fe3O4 catalysts in harsh water–gas shift (WGS) reaction environments. By encapsulating Cu/Fe3O4 with trace RT‐COF‐1, we aimed to preserve the structural integrity and active interfaces between the metal components during catalytic reactions. Characterization techniques, including X‐ray photoelectron spectroscopy, nitrogen sorption, and high‐angle annular dark‐field scanning transmission electron microscopy, confirmed the successful COF coating and its role in preventing particle aggregation and maintaining active site structures over extended catalytic tests. Notably, Cu/Fe3O4@COF demonstrated significantly enhanced stability during a continuous 24‐h WGS test compared to uncoated catalysts, which exhibited rapid deactivation. Mechanistic insights indicated that COF coating reduced the number of active sites while preserving the overall morphology of the catalyst, contributing to its robust performance. Ultimately, this work highlights the potential of COF encapsulation as an effective strategy for enhancing the durability and efficacy of multifunctional catalysts in challenging reaction conditions. [ABSTRACT FROM AUTHOR]

The article presents a mathematical model of the vacuum gas oil hydrocracking process, which takes into account chemical transformations of the grouped components, including n-paraffins C22-C40, iparaffins C22-C40, n-paraffins C5-C21, i-paraffins C5-C21, naphthenes, aromatics, resins, hydrocarbon gas, and the reactions of coke formation and its accumulation on the catalyst surface during the operation cycle. The model also includes the equation for calculation of temperature profile during the process and the equation for calculation of the catalyst activity depending on the content of coke accumulated. The results on the influence of the hydrogen-containing gas consumption and the feedstock flow rate on the coke content on the catalyst, the activity of the catalyst and the temperature profile in the catalyst layers, obtained by calculations using a model, are presented. It is shown that hydrogen-containing gas consumption has optimal values depending on the feedstock flow rate, which ensure the maintenance of the maximum possible catalyst activity and the required depth of feedstock conversion. The optimal consumption of hydrogen-containing gas is determined at different feedstock flow rates. The increase in the feedstock flow rate by 20 m³/h from 220 m³/h to 240 m³/h requires increasing in the hydrogen-containing gas consumption by 500 kg/h from 9500 kg/h to 10000 kg/h. Maintaining hydrogen-gas consumption higher than optimal is impractical because it leads to decrease in the temperature of the process lower than favorable for the target reactions thus decreasing the depth of feedstock conversion with simultaneous increasingly more lower influence on the coke formation and increased operational costs. [ABSTRACT FROM AUTHOR]

Abstract One class of the Ziegler–Natta catalysts (ZNC) – the TiCl4/MgCl2 having triethyl aluminum (AlEt3), has been widely utilized during ethylene polymerization. Although the Ti species plays the role of a major active site, an increase of Ti species does not always improve the activity of ZNC. Herein, investigations of experiments and density functional theory (DFT) elucidate this inverse effect of the increased amount of TiCl4 deposition in ZNC because of the pretreatment process. However, the activity of ZNC on pretreated MgCl2 dropped to 60% of the unpretreated one. The DFT demonstrates that the pretreatment strengthened the interaction between TiCl4 and ZNC, especially on the (104) surface, forming the TiCl4-TiCl4 cluster. The existence of this TiCl4-TiCl4 cluster found on the ZNC (104) surface weakens the adsorption of the first AlEt3 molecule and obstructs further alkylation process, making another Ti site of the alkylated TiCl4-TiCl4 cluster inactive. However, the difficult formation of the TiCl4-TiCl4 cluster found on the ZNC (110) is an important key point that enables the activation of all adsorbed TiCl4 on this surface by facilitating the alkylation process. Moreover, the existence of the MgCl2 (110) surface prevents the formation of the TiCl4-TiCl4 cluster significantly. Hence, it is suggested that the existence of the (110) plane on ZNC plays a key role in controlling the performance of the ZNC, especially the stability via the prevention of deactivation caused by the clustering of TiCl4.

This study consists of four main parts. First, a heterogeneous reactor model was developed to simulate a diesel hydrodesulfurization (HDS) reactor with catalyst deactivation. Second, operating conditions were investigated. Third, the simulation results from the first part were modeled using the response surface method and artificial neural networks (ANNs) to shorten the temperature path optimization time. Among the different modeling methods, the feed-forward ANN method employing the Bayesian Regularization (BR) training method with 10 neurons in the hidden layer demonstrated the highest accuracy. Finally, the temperature path of the trickle bed reactor was optimized. A three-dimensional curve depicting sulfur output content versus temperature and catalyst operation time was plotted using the most effective ANN approach as a fitness function. When the sulfur content met the Euro-6 requirement, the temperature path versus catalyst working period was optimized.

Many catalytic reactions suffer from product inhibition, which especially hard to control in homogeneous hydrogenation due to the scaling relation between the inhibited and active states of the catalyst. We recently reported one such pathway in Mn(I) hydrogenation and demonstrated that addition of alkoxide bases could affect the thermodynamic favorability of this reaction and selectively suppress the product inhibition. Since external reaction promotors are formally not involved in reaction thermodynamics, we set to investigate the explicit molecular interactions behind these apparently environmental effects. Herein, we reveal that the thermodynamic landscape of the inhibitory process exhibits a non‐monotonic dependence on the base concentration. This study related this phenomenon to the presence of two dominant mechanisms operating at different base concentrations. Specifically, the base additives can enhance the ionic strength and lower the free energy of the inhibited state at low promotor concentration. At high base concentrations this study suggested the formation of highly labile alcohol‐alkoxide clusters which stabilize the free alcohol and make its addition to the catalyst unfavourable, thereby suppressing the inhibition. While relatively weak, such noncovalent interactions between reactants and reaction environment can cause substantial perturbations to the free energy of catalytic process, ultimately deciding its fate. [ABSTRACT FROM AUTHOR]

The performance of Cu/ZnO/Al2O3 (CZA) catalysts promoted by addition of CeO2, MnO2 or ZrO2 in direct methanol production from unconventional syngas was experimentally investigated. The unconventional syngas used in this study contain 25% H2, 25% CO, 20% CH4, 20% CO2 and 10% N2, representing biomass‐derived syngas cultivated from an industrial wood chips pyrolysis plant. The catalysts were synthesised using co‐precipitation technique and tested for methanol synthesis in a fixed‐bed reactor. The activity test of the catalysts showed that the addition of CeO2 or ZrO2 to the CZA catalyst improved the methanol yield, albeit with lower selectivity, whereas adding MnO2 enhanced methanol selectivity but decreased the methanol yield. ZrO2‐promoted catalyst showed the best‐improved activity and stability. The calcined and spent catalysts were characterised using X‐ray diffraction (XRD), N2 physisorption, N2O chemisorption, hydrogen temperature‐programmed reduction (H2‐TPR) and X‐ray photoelectron spectroscopy (XPS). The characterisation results indicate that the catalytic activity is dependent on Cu dispersion, Cu‐active surface area, the catalyst reducibility, Brunauer–Emmett–Teller (BET) surface area and the Cu0/Cu+ ratio. In contrast, catalyst stability was related to the proportion of Cu+ among all surface Cu species. [ABSTRACT FROM AUTHOR]

Catalytic ozone oxidation, which is characterized by strong oxidizing properties and environmental friendliness, has been widely used in organic wastewater treatments. However, problems such as a low organic pollutant removal efficiency and unstable operation during the catalytic ozone treatment process for wastewater remain. To address these disadvantages, in this study, the treatment efficacy of catalytic ozone oxidation on a coal chemical reverse osmosis concentrate was investigated. The basic water quality indicators of the chemical reverse osmosis concentrate were analyzed. The effects of initial pollutant concentration, pH, ozone concentration, and catalyst concentration on the COD removal rate from the coal chemical reverse osmosis concentrate were explored. Water quality indicators of the chemical reverse osmosis concentrate before and after the catalytic ozone treatment were studied using spectroscopic analysis methods. The RO concentrate demonstrated large water quality fluctuations, and the catalytic ozonation process removed most of the pollutants from the treated wastewater. A possible deactivation mechanism of the ozone catalyst was also proposed. This study provides a theoretical reference and technical support for the long-term, efficient, and stable removal of organic pollutants from coal chemical reverse osmosis concentrate using a catalytic ozone oxidation process in practical engineering applications. [ABSTRACT FROM AUTHOR]

Low-temperature soot oxidation in catalytic diesel particulate filters (DPF) is important for maintaining high efficiency of heavy-duty vehicles. This can be achieved by coating DPFs with an oxidation catalyst. In this work, catalytic DPFs have been collected from real-world operating heavy-duty vehicles for assessment of their catalytic activity and subsequent characterization. Testing of catalytic activity revealed the diminishing nitric oxide (NO) oxidation of the aged catalysts. The apparent reaction rates showed that the number of available catalytic sites decreased with mileage explaining the loss in activity. Characterization of the samples showed a decreasing surface area as well as an accumulation of metals and poisonous elements. An important finding from SEM-EDS analysis is the evident accumulation of phosphorus and sulfur in the washcoat in the absence of other ash-related elements, potentially explaining the decreased activity.

AbstractMarine fuels are consumed worldwide in quantities of more than 200 million tons per year. It is not a uniform product, but rather heterogeneous mixtures of hydrocarbons with a wide range of viscosities. Due to the production processes, marine diesel contains dimethylsiloxanes. These lead to damage to marine exhaust catalysts in connection with combustion reactions in the ships’ engines. A novel analytical method, presented here, was developed that allows to investigate these processes and to monitor the dimethylsiloxane contents in complex marine fuel matrices. The key steps of the analytical procedure are analyte enrichment by solid phase extraction (SPE) using thermally activated silica gel and chromatographic separation and measurement by heart-cutting gas chromatography - mass spectrometry. Authentic reference substances for quantification by standard addition are used for the dimethylsiloxane analytes. The clean-up enabled a 90% reduction of the matrix content in the analysis solutions compared to the initial sample. Recovery rates in the range of 87.8% to 111.4% were determined for all analytes (Si3 to Si9). The detection limits of analytes ranged from 0.06 μg/L to 5.68 μg/L. Values of 0.71 μg/L to 23.6 μg/L were determined for the limits of quantification. The newly designed analytical method was successfully applied to real marine fuel samples. The analytical procedure is to be made available to commercial and industrial laboratories as a practical method for controlling siloxane contents in marine fuels to contribute this way to efficiently functioning marine exhaust gas purification. [ABSTRACT FROM AUTHOR]

Copyright of Advances in New & Renewable Energy is the property of Editorial Office of Advances in New & Renewable Energy and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A series of model catalysts were obtained by treating commercial fresh and spent catalysts unloaded from the factory with different methods, including green oil dipping, extraction and high-temperature regeneration; finally, the deactivation behavior of the commercial catalyst for acetylene hydrogenation were studied. The influence of various possible deactivation factors on the catalytic performance was elucidated via detailed structural characterization, surface composition analysis, and activity evaluation. The results showed that green oil, carbon deposit and sintering of active metal were the main reasons for deactivation, among which green oil and carbon deposit led to rapid deactivation, while the activity could be recovered after regeneration by high-temperature calcination. The sintering of active metal components was attributed to the high-temperature regeneration in hydrothermal conditions, which was slow but irreversible and accounted for permanent deactivation. Thus, optimizing the regeneration is expected to extend the service life of the commercial catalyst. [ABSTRACT FROM AUTHOR]

The catalytic conversion of naturally rich and renewable biomass into high-value chemicals is of great significance for pursuing a sustainable future and a green economy. The preparation of pentanediol from furfuryl alcohol is an important means of high-value conversion of biomass. The Pt-based catalyst supported on MgO was applied to the selective hydrogenation of biomass furfuryl alcohol to prepare pentanediol. By adjusting parameters such as catalyst loading, reduction temperature, reaction temperature, and pressure, a highly active catalyst was designed and the optimal catalytic hydrogenation conditions were determined. The hydrogenation experiment results showed that the selectivity of the 2Pt/MgO-200 catalyst for 1,2-pentanediol and 1,5-pentanediol reached 59.4% and 15.2%, respectively, under 160 °C and 1 MPa hydrogen pressure. The catalyst was characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectrometer (XPS), CO2-temperature programmed desorption (CO2-TPD), and other methods. The characterization results indicate that the reduction temperature has a significant impact on the metal Pt, and an appropriate reduction temperature is beneficial for the hydrogenation performance of the catalyst. In addition, the basic sites on the carrier are also another important factor affecting the activity of the catalyst. In addition, stability tests were conducted on the catalyst, and the reasons for catalyst deactivation were studied using methods such as thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FT-IR). The results showed that the activity of the catalyst decreased after five cycles, and the deactivation was due to the hydrolysis of the carrier, the increase in metal particle size, and the surface adsorption of organic matter. [ABSTRACT FROM AUTHOR]

This study consists of four main parts. First, a heterogeneous reactor model was developed to simulate a diesel hydrodesulfurization (HDS) reactor with catalyst deactivation. Second, operating conditions were investigated. Third, the simulation results from the first part were modeled using the response surface method and artificial neural networks (ANNs) to shorten the temperature path optimization time. Among the different modeling methods, the feed-forward ANN method employing the Bayesian Regularization (BR) training method with 10 neurons in the hidden layer demonstrated the highest accuracy. Finally, the temperature path of the trickle bed reactor was optimized. A three-dimensional curve depicting sulfur output content versus temperature and catalyst operation time was plotted using the most effective ANN approach as a fitness function. When the sulfur content met the Euro-6 requirement, the temperature path versus catalyst working period was optimized. [ABSTRACT FROM AUTHOR]

The catalytic production of diphenylmethane from the reaction of benzene with benzyl alcohol was investigated using HZSM-12 and desilicated HZSM-12 that was obtained by treating ZSM-12 with 0.2M NaOH solution at 85 °C for 60 min. The untreated and alkaline treated ZSM-12 zeolites were characterized by X-ray diffraction, nitrogen adsorption/desorption isotherms, scanning electron microscopy, inductively coupled plasma optical emission spectrometry, and temperature-programmed desorption of ammonia. The desilicated HZSM-12 showed promising catalytic performance with benzyl alcohol conversion of 100% and the selectivity to diphenylmethane of 74% and 87% in 4 h and 8 h reaction time, respectively. The reaction parameters affecting benzyl alcohol conversion and product distribution were also presented. The activities of fresh and regenerated catalysts were compared, and characterization results indicated that the occluded organic molecules decreased the number of acidic sites of the catalyst after the reaction and regeneration.