Effect Of Different Catalysts Research Articles

Enhancing biomass gasification: A comparative study of catalyst applications in updraft and modifiable-downdraft fixed bed reactors

This study aims to investigate the effects of different catalysts on biomass gasification. Therefore, red mud (RM) and Aluminum–Nickel alloy were used as catalysts with biomass mixture (BM) for the lab-scale gasification studies by using an updraft and a modifiable-downdraft fixed bed reactor. The maximum volumetric percentage of H2, ranging from 51% to 65%, was achieved at 900 °C in both gasifiers. Al–Ni catalyst significantly boosted H2 content, reaching 65% in the updraft gasifier at 900 °C with 0.05 L/min dry air. H2/CO ratio varied from 2 to 4 for BM, while catalyst use expanded the range to 1.6–7 with the Al–Ni catalyst demonstrating the most effective performance. In general, it was seen that RM increased the H2 component in the syngas between 1 and 7 vol% at 900 °C in updraft gasifier. In the modifiable-downdraft reactor, on the contrary, H2 concentration in the syngas decreased by 2–6% with the addition of RM.

Research Advances on Cyclohexane Catalytic Cracking

This article elaborates on the research achievements of domestic and foreign researchers in exploring the conversion pathways and reaction mechanisms of cyclohexane catalytic cracking in recent years. It analyzes the effects of different catalysts and process conditions on the conversion laws of cyclohexane, summarizes the conversion pathways of cyclohexane, and discusses the chemical mechanisms of several main reactions of cyclohexane in catalytic cracking, such as cracking, isomerization, hydrogen transfer, dehydrogenation, and alkylation; Several advanced characterization methods and common research methods were listed, and prospects for future development in this field were proposed based on existing research.

Transition-Metal Catalyzed Synthesis of Pyrimidines: Recent Advances, Mechanism, Scope and Future Perspectives.

Pyrimidine is a pharmacologically important moiety that exhibits diverse biological activities. This review reflects the growing significance of transition metal-catalyzed reactions for the synthesis of pyrimidines (with no discussion being made on the transition metal-catalyzed functionalization of pyrimidines). The effect of different catalysts on the selectivity/yields of pyrimidines and catalyst recyclability (wherever applicable) are described, together with attempts to illustrate the role of the catalyst through mechanisms. Although several methods have been researched for synthesizing this privileged scaffold, there has been a considerable push to expand transition metal-catalyzed, sustainable, efficient and selective synthetic strategies leading to pyrimidines. The aim of the authors with this update (2017-2023) is to drive the designing of new transition metal-mediated protocols for pyrimidine synthesis.

High-throughput experimentation for photocatalytic water purification in practical environments

High-throughput screening instrument was developed for photocatalytic water purification, enabling the simultaneous testing of 132 photocatalytic reactions under uniform visible light irradiation, temperature control, and stirring. The instrument was used to investigate the effects of different catalysts (TiO2, ZnO, α-Fe2O3) and environmental waters (seawater, urban wastewater, and industrial wastewater) on dye degradation. It was observed environmental ions, particularly carbonate and phosphate ions, significantly reduced catalyst activity by inhibiting the adsorption of dye molecules. To develop effective catalysts for dye degradation in industrial wastewater, 15 types of noble metal nanoparticles (NPs) were supported on photocatalysts. The study found that noble metal NPs with high work functions and oxidation resistance, such as Au and Pt, exhibited higher activity even in the industrial wastewater, likely converting environmental ions into active species. These findings, based on 432 test results, demonstrate the effectiveness of the developed high-throughput screening instrument for optimizing photocatalytic water purification.

Efficient degradation of ciprofloxacin in wastewater by CuFe2O4/CuS photocatalyst activated peroxynomosulfate

In this study, CuFe2O4/CuS composite photocatalysts were successfully synthesized for the activation of peroxynomosulfate to remove ciprofloxacin from wastewater. The structural composition and morphology of the materials were analyzed by XRD, SEM, TEM, and Raman spectroscopy. The electrochemical properties of the samples were tested by an electrochemical workstation. The band gap of the samples was calculated by DFT and compared with the experimental values. The effects of different catalysts, oxidant PMS concentrations, and coexisting ions on the experiments were investigated. The reusability and stability of the photocatalysts were also investigated. The mechanism of the photocatalytic degradation process was proposed based on the free radical trapping experiment. The results show that the p-p heterojunction formed between the two contact surfaces of the CuFe2O4 nanoparticle and CuS promoted the charge transfer between the interfaces and inhibited the recombination of electrons and holes. CuFe2O4-5/CuS photocatalyst has the best catalytic activity, and the removal rate of ciprofloxacin is 93.7%. The intermediates in the degradation process were tested by liquid chromatography-mass spectrometry (LC-MS), and the molecular structure characteristics of ciprofloxacin were analyzed by combining with DFT calculations. The possible degradation pathways of pollutants were proposed. This study reveals the great potential of the photocatalyst CuFe2O4/CuS in the activation of PMS for the degradation of ciprofloxacin wastewater.

The Catalytic Curing Reaction and Mechanical Properties of a New Composite Resin Matrix Material for Rocket Fuel Storage Tanks

In this paper, an equimolar blend of bisphenol A dipropargyl ether and cyanate ester was selected to study the effect of different catalysts on the curing reaction of a bisphenol A dipropargyl ether and cyanate ester blended resin system, and the thermal stability and mechanical properties of the catalytically cured blended resin system were investigated. Acetylacetone salts of transition metals and dibutyl ditin laurate reduced the curing temperature of bisphenol AF-type di cyanate ester, and copper acetylacetonate at a mass fraction of 0.3% significantly reduced the curing temperature of bisphenol AF-type di cyanate ester to less than 473 K. Bisphenol A dipropargyl ether pr-polymerized and equimolarly blended with bisphenol A di cyanate ester and bisphenol E-type di cyanate ester also cured below 473 K under the same conditions. Among the cured compounds of the blended resins of bisphenol A dipropargyl ether with bisphenol AF-type di cyanate ester, bisphenol A-type di cyanate ester and bisphenol E-type di cyanate ester, the blended resins of bisphenol A-type di cyanate ester and bisphenol E-type di cyanate ester have better overall performance. The residual rate of 873 K in air was 38%, and the flexural strength, flexural modulus, and impact strength were 129.4 MPa, 4.3 GPa, and 27.3 kJ·m−2, respectively. This kind of blended resin is expected to be used in the liquid oxygen storage tanks of rockets.

A review of CO2 catalytic regeneration research based on MEA solution

In recent years, the rapid increase of CO2 emission has caused severe environmental issues. The environmental concern has made how to reduce the carbon emissions become a hot topic. Many scholars and research teams believe that the organic amine chemical absorption technology is the most favored and promising carbon capture technology due to its highly CO2 removal effectiveness. However, it is not applied wildly in industrial environment since the desorption process energy consumption is too much, over 4 GJ/t CO2. Many researchers report that catalysts can help to reduce the desorption energy. And it is generally assumed that four key properties of solid acid catalysts determined the performance of solid acid catalysts in the process of CO2 desorption: the total number of acid sites; specific surface area; the ratio of Brønsted acid sites to Lewis acid sites; the amount of Brønsted acid sites. Therefore, this paper reviews the recent research on the effect of different catalysts on the energy consumption of CO2 desorption and the progress of research on improving catalyst performance. Also, it provides views on the possible problems in practical industrial applications.

Recent Advances in Biomass Pyrolysis Processes for Bioenergy Production: Optimization of Operating Conditions

Bioenergy has emerged to be among the primary choices for the short- and medium-term replacement of fossil fuels and the reduction in greenhouse gas (GHG) emissions. The most practical method for transforming biomass into biofuel is thermochemical conversion, which may be broken down into combustion, torrefaction, pyrolysis, hydrothermal liquefaction, and gasification. In this study, producing biofuels using a biomass pyrolysis process was investigated. This study explored the pyrolysis process and operating conditions to optimize the process parameters to maximize the desired product yields and quality. The pyrolysis process produces three main products, which are bio-oil, bio-char, and gas. There are three classifications for the pyrolysis method, with each of them producing a majority of a certain product. First, slow pyrolysis is conducted in the temperature range of 300–950 °C and residence time of 330–550 s. It produces around a 30% oil yield and 35% char yield, and thus, the majority yield of slow pyrolysis is char. Second, fast pyrolysis produces around 50% oil, 20% char, and 30% gas yields with a temperature range of 850–1250 °C and a residence time of 0.5–10 s. The average yield of flash pyrolysis was found to be 75% bio-oil, 12% bio-char, and 15% gas, which is conducted within less than 1 s. It was reported that the pyrolysis of biomass was simulated using ASPEN Plus, where the effects of several parameters, such as the temperature, heating rate, and residence time, on the product yield and composition were investigated. Pyrolysis was performed under different conditions ranging from 400 to 600 °C. The effects of different catalysts on the pyrolysis process were studied. It was found that the addition of a catalyst could increase the yield of bio-oil and improve the quality of the product. The optimal operating condition for the pyrolysis process was determined to be a temperature of 500 °C, which resulted in a higher bio-oil yield. It was found that the biofuel yield was enhanced by selecting appropriate raw materials, such as rice husk, along with the pyrolysis temperature (e.g., 450 °C) and particle size (350–800 µm), and using a low residence time and pressure.

Solvent-free oxidation of p-tert-butyl toluene catalyzed with cobalt 4-tert-butylbenzoate in an internal circulation bubbling bed reactor

P-tert-butyl benzoic acid (PTBA) was synthesized by solvent-free oxidation of p-tert-butyl toluene (PTBT) at atmospheric pressure using cobalt 4-tert-butylbenzoate as catalyst and oxygen as an oxidant in a self-made internal circulation bubbling bed reactor (ICBBR). The effects of different catalysts and reactors on the reaction were investigated. The results show that the catalytic performance of cobalt 4-tert-butylbenzoate is superior, and the performance of the ICBBR is distinctly better than that of the batch stirred tank reactor (BSTR). The effects of reaction conditions such as flow rate, reaction temperature, and catalyst concentration on the oxidation of PTBT were studied. According to the distribution and kinetics of oxidation products, the oxidation mechanism of PTBT was analyzed. The results show that under the conditions of the oxygen flow rate of 2.5 L/min, reaction temperature of 150 °C and Co mass fraction of 250 ppm, the conversion rate of PTBT is 45.63% and the selectivity of PTBA is 97.8% after 4 h reaction without solvent. The reaction kinetics model of oxidation of PTBT to PTBA was established, and the reaction kinetics equation was obtained. The experimental values were close to the predicted values of the model.

Wadsworth–Emmons Reaction by Using the Fluorapatite Catalyst: Kinetic Studies

Wadsworth–Emmons reaction was successfully carried out by using the fluorapatite (FAP) catalyst. The reaction of 2-methoxybenzaldehyde and triethylphosphonoacetate using FAP afforded α,β-unsaturated ester with 100% conversion and 80% selectivity. A kinetic model was validated at different temperatures by Langmuir–Hinshelwood–Hougen–Watson (LHHW), and the absence of mass transfer resistance was verified by the Weisz Prater criterion. The effect of different catalysts, temperature, catalyst loading, solvent, mole ratio, and speed of stirring was studied. The FAP catalyst was characterized by Fourier transform infrared spectroscopy, Brunauer–Emmett–Teller method, nitrogen adsorption–desorption, transmission electron microscopy, energy-dispersive X-ray spectroscopy, temperature programmed desorption (TPD-NH3), X-ray diffraction, and X-ray photoelectron spectroscopy. The FAP catalyst was found to be stable up to three recycles with no loss in activity.

Imine Oxidation Catalyzed by Zinc Hydroxyapatite: Kinetic Studies

AbstractThe synthesis of N,N‐diphenylformamide from N‐benzylideneaniline and urea hydrogen peroxide is investigated using a zinc hydroxyapatite (ZnHAP) catalyst. It was found that the catalyst resulted in the highest activity of 91 % conversion and 40 % selectivity at 130 °C in 2 h. A kinetic model was validated by Langmuir‐Hinshelwood‐Hougen‐Watson (LHHW) at different temperatures and the absence of mass transfer resistance was proved by the Weisz Prater criterion. Effect of different catalysts, catalyst loading, temperature, mole‐ratio, and speed of stirring was studied. The as‐synthesized catalyst is characterized by FTIR, BET nitrogen adsorption‐desorption, TEM, EDX, TPD‐NH3, XPS, ICP‐MS and XRD. ZnHAP catalyst was found to be stable up to three recycles with no loss in activity.

Efficient Pyrolysis of Low-Density Polyethylene for Regulatable Oil and Gas Products by ZSM-5, HY and MCM-41 Catalysts

In this research, catalytic cracking of low-density polyethylene (LDPE) has been carried out in the presence of three kinds of typical molecular sieves, including ZSM-5, HY and MCM-41, respectively. The effects of different catalysts on the composition and quantity of pyrolysis products consisting of gas, oil and solid material were systematically investigated and summarized. Specially, the three kinds of catalysts were added into LDPE for pyrolysis to obtain regulatable oil and gas products (H2, CH4 and a mixture of C2–C4+ gaseous hydrocarbons). These catalysts were characterized with BET, NH3-TPD, SEM and TEM. The results show that the addition of MCM-41 improved the oil yield, indicating that the secondary cracking of intermediate species in primary pyrolysis decreased with the case of the catalyst. The highest selectivity of MCM-41 to liquid oil (78.4% at 650 °C) may be attributed to its moderate total acidity and relatively high BET surface area. The ZSM-5 and HY were found to produce a great amount of gas products (61.4% and 67.1% at 650 °C). In particular, the aromatic yield of oil production reached the maximum (65.9% at 500 °C) when the ZSM-5 was used. Accordingly, with the three kinds of catalysts, a new environment-friendly and efficient recovery approach may be developed to obtain regulatable and valuable products by pyrolysis of LDPE-type plastic wastes.

Effects of different catalysts on the mechanical, thermal, and rheological properties of poly(lactic acid)/polycarbonate blend

Effects of different catalysts on the mechanical, thermal, and rheological properties of poly(lactic acid)/polycarbonate blend

Comparative study of the catalytic co-pyrolysis of microalgae (Chlorella Vulgaris) and polypropylene with acid and base catalysts toward valuable chemicals production

The co-pyrolysis of microalgae with plastic for valuable chemical production is promising to address the inferiority of microalgae conversion while solving waste plastic problems. A deep understanding of the synergistic effects of different catalysts on the co-pyrolysis and reaction pathways could promote process intensification through interpreting the kinetics and product characterizations. The thermogravimetric analyzer (TGA), diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), and thermal cracking-gas chromatography/mass spectrometer (py-GC/MS) facilitated the understanding of the process. The weight-loss rates of the catalytic co-pyrolysis showed a pattern of non-catalytic < CaO < ZSM-5. The experimental and theoretical values of the co-pyrolysis activation energy were 114.99 kJ/mol and 194.80 kJ/mol, respectively. ZSM-5 reduced the co-pyrolysis activation energy, while CaO had the opposite effects. Both CaO and ZSM-5 reduced the compositions of the oxygen- and nitrogen-containing groups in the pyrolysis product, but CaO preferred oxygen removal, and ZSM-5 favored the nitrogen removal. ZSM-5 was selective for aromatic hydrocarbons conversion (from 12.23% to 14.56%), while CaO was more inclined to aliphatic hydrocarbons formation (from 70.67% to 80.95%).

Experimental Study on the Catalyst-Coated Membrane of a Proton Exchange Membrane Electrolyzer

Proton exchange membrane (PEM) technology may regulate the electrical grid connected to intermittent power sources. The growing pace of R&amp;D in alternative components is widening manufacturing methods and testing procedures across the literature. This turns the comparison between performances into a more laborious task, especially for those starting research in this area, increasing the importance of testing components accessible to all. In this study, an electrochemical characterization is performed on a commercial single-cell PEM water electrolyzer with commercial catalyst-coated membranes (CCMs) and one prepared in-house. Two membrane thicknesses and the effect of different catalysts are assessed. The thicker membrane, Nafion 117, operates with 5% greater ohmic overvoltage than the thinner Nafion 115, resulting in up to 1.5% higher voltage for the former membrane. Equivalent Ir black CCMs provided by different suppliers and one prepared in-house perform similarly. Regarding the influence of the anode catalyst, Ir black, IrRuOx and IrRuOx/Pt have similar performance, whereas IrOx has worse performance. Compared with Ir black, the mix of IrRuOx/Pt operated with 1.5% lower voltage at 2.6 A cm−2, whereas IrRuOx performed with 2% lower voltage at 0.3 A cm−2. A temporary increase in performance is observed when the anode is purged with hydrogen gas.

S‐g‐C3N4/N−TiO2 @PTFE Membrane for Photocatalytic Degradation of Tetracycline

AbstractHerein we synthesized S‐g‐C3N4 and N−TiO2 catalysts by hydrothermal and calcination technologies and SCN/NT@PTFE membrane by a vacuum filtration method. The morphology and composition of the synthesized materials were analyzed by different characterization methods (SEM/HRTEM/XRD/XPS/UV‐vis et.). The effects of different catalysts, pollutant concentrations, mass of catalyst and pH on the photo‐degradation of tetracycline were investigated. The degradation rate of tetracycline by SCN/NT‐2@PTFE membrane was as high as 99.9 % after 2 h of illumination. This was mainly because heterogeneous structure between S‐g‐C3N4 and N−TiO2 broadened the light absorption range and suppressed the carrier complex. Superoxide radicals (⋅O2−) were proved to play a dominant role in the degradation reaction. After 20 days of stirring in water, the photocatalytic performance of membrane decreased slightly, demonstrating its good stability. The study of SCN/NT‐2@PTFE membrane provides a new direction for the development of photocatalysis and membrane.

Review on Catalytic Biomass Gasification for Hydrogen Production as a Sustainable Energy Form and Social, Technological, Economic, Environmental, and Political Analysis of Catalysts.

Sustainable energy production is a worldwide concern due to the adverse effects and limited availability of fossil fuels, requiring the development of suitable environmentally friendly alternatives. Hydrogen is considered a sustainable future energy source owing to its unique properties as a clean and nontoxic fuel with high energy yield and abundance. Hydrogen can be produced through renewable and nonrenewable sources where the production method and feedstock used are indicators of whether they are carbon-neutral or not. Biomass is one of the renewable hydrogen sources that is also available in large quantities and can be used in different conversion methods to produce fuel, heat, chemicals, etc. Biomass gasification is a promising technology to generate carbon-neutral hydrogen. However, tar production during this process is the biggest obstacle limiting hydrogen production and commercialization of biomass gasification technology. This review focuses on hydrogen production through catalytic biomass gasification. The effect of different catalysts to enhance hydrogen production is reviewed, and social, technological, economic, environmental, and political (STEEP) analysis of catalysts is carried out to demonstrate challenges in the field and the development of catalysts.

Designing dual-defective photocatalyst of Z-scheme H-BiVO4/D-NG composite with hollow structures for efficient visible-light photocatalysis of organic pollutants

Photocatalytic degradation using sunlight is attractive due to its high efficiency, low cost and environmental friendliness. This study successfully synthesized a dual-defective H-BiVO4/D-NG hollow structure photocatalyst was discretely decorating hollow BiVO4 (H-BiVO4) on dual defect graphene (D-NG) by hydrothermal method. The characterization of the structure, morphology, optical and electrochemical properties was carried out. The effects of different catalysts, annealing temperature, catalyst dosage and different reaction temperature on the photocatalytic degradation of BPA were investigated to explore the property of photocatalytic reactor. Especially, the H-BiVO4/D-NG composite showed the highest photocatalytic activity, which could degrade 98% of BPA in 30 min and remove 81% of total organic carbon (TOC) in 120 min. In addition, the cycling experiments and XRD patterns before and after the photocatalytic reaction showed that the catalyst exhibited outstanding stability, which is conducive to practical applications in the field of photocatalysis. Furthermore, electron spin resonance (ESR) and active radical trapping experiment indicated that the prepared nanocomposites followed a direct Z-scheme mechanism. The results showed that a combined strategy of introducing defect engineering and morphology control in photocatalyst design can effectively improve photocatalytic activity. It's expected to provide new ideas for the preparation of high-performance photocatalysts.

Photocatalytic degradation of salicylic acid employing TIO2 and ZNO in aqueous suspension / Degradação fotocatalítica do ácido salicílico empregando TIO2 e ZNO em suspensão aquosa

The photocatalytic degradation of salicylic acid (SA) in reduced concentration (14.5 µmol L-1) was investigated using TiO2 and ZnO as photocatalysts under irradiation with UV light using UV-Vis spectrophotometry and HPLC analysis. The effect of different catalysts and catalyst loading, kinetic analysis, and dissolution of ZnO using the experimental conditions adopted were evaluated in acidic medium (pH = 3.0). Chronic ecotoxicity tests of the effluent from the reactions were conducted employing a concentration of 1 g L-1 of photocatalysts. The results showed that TiO2 and ZnO presented very similar performance for the SA degradation, whose profile followed first-order kinetics. The dissolution of ZnO observed was low using the experimental conditions adopted. Chronic ecotoxicity tests carried out showed that the use of ZnO/UV system for degradation of SA leads to a product with significant harmful effects on Ceriodaphnia dubia, even at reduced concentrations of the effluent from the reaction.

Study on Selective Preparation of Phenolic Products from Lignin over Ru–Ni Bimetallic Catalysts Supported on Modified HY Zeolite

The catalytic depolymerization of organic solvent lignin with the prepared catalyst 2.5Ru–10Ni/Al-HY was investigated in a high-pressure reactor. Effects of different catalysts, temperature, time, recyclability for catalyst, and solvents on the catalytic performance were explored. The optimal reaction conditions were reaction time 5 h and temperature 280 °C in ethanol solvent. As a result, the highest yield of phenolic monomers was 20.2 wt %, the yield of solid residue was only 4.8 wt %, and the gas products were CH4, C2H6, and CO mainly. With the increase of cycle times, the catalyst had no obvious deactivation, indicating a unique cycle stability. Through NMR characterization of lignin and depolymerization products, it was found that the signals of the original structures (A, B, and C) in lignin disappeared after reaction. According to the analysis of the reaction path, the depolymerization of lignin mainly included the depolymerization of lignin into reaction intermediates and the formation of phenolic compounds by breaking chemical bonds. This research showed a method for preparing phenolic products by the molecular sieve catalyzed depolymerization of lignin.