Amount Of Catalyst Research Articles

Selective Carbohydrate Deacetylation: Simple and Mild Approach based on Supported Copper Nanoparticles

AbstractHerein, a selective protocol for the complete removal of acetyl protecting groups from carbohydrate derivatives based on copper nanoparticles supported on activated carbon is presented. The deacetylation procedure occurs under neutral conditions, is applicable to a wide range of substrates and tolerates a variety of functional groups (e. g. azido, allyl and silyl groups). Quantitative yields of the deacetylated product were obtained for all evaluated derivatives using catalyst amounts between 1 and 10 mol%. As a special highlight, the dual behavior of the nanocatalyst in both deacetylation and click reactions is reported.

Effect of catalyst and oxidant concentrations in a TEMPO oxidation system on the production of cellulose nanofibers.

In traditional TEMPO oxidation systems, the high cost of TEMPO catalysts has been a significant barrier to the industrialization of oxidized CNF. From an economic perspective, presenting the characteristics of various CNFs produced with the oxidation systems with reduced catalyst usage could facilitate the industrial application of CNF across a wide range of fields. In this study, it was demonstrated that reducing the amount of TEMPO catalyst used (from 0.1 to 0.05 mmol g-1) in a conventional oxidation system increased the carboxylate content by approximately 6.3%. Furthermore, the activation of hydroxyl amine TEMPO, which is generated after the oxidation reaction of cellulose, was enhanced by adjusting the dosage of the inexpensive oxidant NaClO, leading to a 20% improvement in carboxylate content. This suggests that controlling the amount of NaClO as an oxidant can be a key parameter in adjusting the dosage of TEMPO to achieve the targeted degree of surface substitution. Results from the dispersion stability, UV-transmittance, and morphological properties of TEMPO-oxidized CNF using microfluidizing treatment showed that high carboxylate content plays a crucial role in producing high-purity CNF suspensions, which are small, uniform, and free from microfibers. Additionally, by varying the number of mechanical treatments applied to the oxidized cellulose, various types of CNF suspensions with different mean widths were obtained. We expect that these findings offer meaningful insights to end-users seeking a breakthrough in the performance limitations of final applications using cellulose nanomaterials.

Optimization of aluminum hydroxide catalyst for efficient hydrogen generation from aluminum-water reaction

The aluminum-water reaction offers a promising method for clean hydrogen production, but it requires an effective catalyst. This study investigates the use of aluminum hydroxide (Al(OH)3) as a catalyst for the aluminum-water reaction to generate hydrogen gas. Various aluminum hydroxide catalysts were synthesized and evaluated for their catalytic performance. The effects of catalyst source, synthesis conditions, quantity, and pH value of the reacting solution were systematically studied. The results demonstrate that self-synthesized, nano-sized Al(OH)3 catalysts exhibit superior catalytic activity compared to commercial sources. Additionally, optimizing the pH value was found to significantly impact the hydrogen generation rate. Proper synthesized Al(OH)3 is capable of completing hydrogen generation within 160 s at pH 11.6, while slightly higher pH value accelerates this reaction down to 60 s. Comparative studies with uncatalyzed reactions at higher pH levels (up to 14) showed significantly slower and incomplete hydrogen production. This research provides insights into developing efficient and sustainable catalytic systems for aluminum-water based hydrogen production.

Oxidation of Geraniol on Vermiculite—The Influence of Selected Parameters on the Oxidation Process

Geraniol is a compound belonging to the group of monoterpenes that finds many applications in organic syntheses, medicine and cosmetics. The following properties of geraniol and its derivatives are of particular interest in medicine: its anti-inflammatory, antioxidant, antimicrobial and anticancer effects. The geraniol oxidation process was carried out using a mineral of natural origin—vermiculite. Vermiculite is a catalyst that perfectly fits into modern trends in the organic industry, where the aim is to use cheap, renewable and relatively easily available catalytic materials (vermiculite is found on continents including Africa, North America, South America, Australia and Asia). Preliminary studies on the oxidation process of geraniol on vermiculite was carried out in a glass apparatus using molecular oxygen supplied by means of a bubbler and magnetic stirrer with a heating function. During the oxidation process of geraniol on vermiculite, the influence of the following parameters was examined: the temperature, amount of catalyst and reaction time. The main parameters of the process, on the basis of which the most favorable process conditions were selected, were the selectivity of the transformation to 2,3-epoxygeraniol, citral and 2,3-epoxycitral, and the conversion of geraniol. The composition of the post-reaction mixtures was determined qualitatively and quantitatively using the gas chromatography method. In addition, vermiculite was subjected to instrumental tests, such as XRD, SEM, EDX, FTIR and UV-VIS. Moreover, the specific surface area, pore volume and pore volume distribution were estimated on the basis of N2 sorption at −196 °C and also the acid-site concentration in vermiculite was established.

Green synthesis of ZnO and Ni-doped ZnO from okra stalks for the photocatalytic degradation of Procion Red MX-5B

This study investigates the photocatalytic degradation of Procion Red MX-5B (PRM) using ZnO and Ni-doped ZnO catalysts derived from okra stalks through a green synthesis method. Various parameters, including hydrogen peroxide concentration (HPC), catalyst amount, nickel (Ni) doping amount, initial PRM concentration, and pH, are systematically studied to assess their impact on PRM degradation efficiency. The results reveal that both ZnO and Ni-doped ZnO catalysts exhibit promising photocatalytic activity, with the highest PRM degradation efficiency achieved at the following reaction conditions: 6 mM of HPC, 40 mg of Ni(7%):ZnO catalyst, 10 ppm initial PRM concentration, and pH = 6. Under these conditions, the Ni-doped ZnO catalyst demonstrated a degradation efficiency of 98.08% compared to 82.99% for the ZnO catalyst. The study highlights the potential of these catalysts for efficient organic pollutant removal and provides valuable insights into the factors influencing their photocatalytic performance.

Effects of nickel substitution on structural, magnetic and optical properties of Sillenite bismuth ferrite nanoparticles

The Ni-doped Bi25FeO40 nanoparticles [Bi25 NixFe(1-x)O40, x = 0.1, 0.3, and 0.5] were synthesized by the hydrothermal method at a temperature of 180 °C. The effects of the Ni substitute on the structural, optical, magnetic, and photocatalytic performance have been investigated. The successful synthesis of the materials was confirmed by Rietveld's refined powder X-ray diffraction and Fourier transform infrared spectroscopy. Scanning electron microscopy together with energy dispersive X-ray spectroscopy (EDS) revealed the morphology of the synthesized nanomaterials as well as its chemical composition. The studied materials exhibited anomalous magnetic properties as evident from the vibrating sample magnetometry (VSM) analysis. These features display a weak ferromagnetic nature and demonstrate increased magnetization when doping elements are incorporated. Furthermore, Optical analysis revealed that bandgaps of Bi25NixFe(1-x)O40 were found to be increased from 2.06 eV to 2.31 eV with increasing Ni content. Additionally, the expansion of sillenite bismuth nickel ferrite's optical bandgap was further confirmed by the photocatalytic degradation of methylene blue as a model dye under the low-power white LED illumination. Lower bandgap undoped nanoparticles showed the highest photocatalytic efficiency, with a degradation rate of ∼43.11 % compared to higher bandgap doped nanoparticles, without adjustment of any reaction conditions such as pH or catalyst amount. The kinetic reaction rate of undoped Bi25FeO40 was roughly twice as fast as that of the material doped with 50 % Ni.

Cross-linking matters: Building hard carbons with enhanced sodium-ion storage plateau capacities

Hard carbon is a promising anode material for sodium-ion batteries (SIBs). However, its commercialization is hampered by its relatively low capacity. This limitation primarily arises from the insufficient closed pore structures developed within the hard carbon. In this contribution, we precisely control the crosslinking structures of phenol-formaldehyde resin precursors by adjusting the catalyst amount, producing carbon materials with varied microstructures. We explore the relationship between the microstructures of the resin-derived hard carbon and its sodium storage performance. Our findings indicate that increasing the crosslinking degree of phenol-formaldehyde resins enhances the number of closed pores formed during high-temperature carbonization, thereby improving the plateau capacity. Notably, the hard carbon exhibits superior rate performance, due to its smaller closed pore diameter. This study provides an in-depth exploration of the relationship between precursor structural characteristics and the microstructures of hard carbons. By calculating the closed pore parameters, we elucidate the structure-performance relationship, demonstrating that optimizing the closed pore structures significantly enhances the electrochemical performance of hard carbons for SIBs. This research offers valuable insights for the development of high-performance hard carbon anodes, paving the way for the commercialization of SIBs.

Optimization study and application of box-behnken model for probing eggshell supported transition metals based catalysts to synthesize hydrazone & dihydropyrimidinones

Solid supported catalysts have several synthetic applications. Herein, finely ground eggshells were used as a solid support for the preparation of transition metal (Ni, Zn, Cu, Sn and Co) based catalysts to synthesize 2,4-dinitrophenylhydrazone (3) and dihydropyrimidinones (7 and 8). The effect of catalyst load, time and temperature on product yield was studied. Box Behnken Model was employed, and three predictors named catalyst amount (A), reaction time (B), and reaction temperature (C) were used to find the correlation of the predictors with the yield. Second order polynomial equation was used to estimate the effects of these factors. According to the statistical model, about 12% increase in yield was observed as a result of one-unit increase in reaction time while all other terms were kept constant. The values of S (18.1616) and R2 (71.2%) indicate that the statistical model gave an adequate fit to data. Quadratic model for the response surface was used for the analysis of variance (ANOVA) results, the larger F-values, and smaller p-values indicated that the predictors are in good agreement. The linear model terms of predictors were found to be significantly effective for yield (P < 0.05). The response surface and contour plots were also in agreement with the predicted model.

Synthesis, Magnetic, and Photocatalytic Activity of Polypyrrole-Based TiO2–Fe Catalyst for Wastewater Treatment

The primary aim of this study is to investigate the degradation efficacy of the Ppy/TiO2-Fe photocatalyst for MB dye in an aqueous solution. Firstly, the direct addition of TiO2 and Fe was done to prepare Ppy/TiO2-Fe photocatalyst. Fourier transformation infrared spectroscopy, XRD, SEM, BET surface area analysis, and magnetization tests established the formation of the Ppy/TiO2-Fe photocatalyst. The crystallite sizes of TiO2, Fe-TiO2, and Ppy/TiO2-Fe photocatalyst were estimated to be 24.99 nm, 21.94 nm, and 21.84 nm, respectively. For the synthesis confirmation, the FTIR spectrum confirmed the existence of Ti-O, Fe-O, and Ppy-related bonds. While comparing the SEM images, the impact of polypyrrole on the particle shape was observed with less aggregation and increased surface roughness. The VSM analysis revealed that incorporating polypyrrole (Ppy) into Fe-TiO2 significantly enhances its magnetic properties, with Ppy/TiO2-Fe exhibiting superparamagnetic behavior, characterized by a higher saturation magnetization (Ms) of 33.11 emu/g and a lower coercivity (Hc) of 0.160 Oe, compared to Fe-TiO2’s Ms of 1.09 emu/g and Hc of 341.39 Oe. The N2 sorption desorption, with a specific surface area of 2.25 × 102 m2/g, is beneficial for photocatalytic activity. The concentration of dye, amount of catalyst, pH, and temperature were studied to evaluate the photocatalytic efficiency of the synthesized Ppy/TiO2-Fe photocatalyst under different conditions. The findings revealed a degradation efficiency of 91.92%. The degradation rate reached 91.92% under optimal conditions within 120 min and could be fitted well by first-order kinetics. The photocatalytic efficiency was also evaluated for the scavenger, and the concentration of H2O2 and the reusability of the catalyst were demonstrated. Based on the observed results, the Ppy/TiO2-Fe photocatalyst could be applied more effectively and efficiently to photocatalytic degradation of organic dyes in wastewater treatment.

Walnut Shell Biomass Triggered Formation of Fe3C-Biochar Composite for Removal of Diclofenac by Activating Percarbonate

Percarbonate (SPC) as a promising substitute for liquid H2O2 has many advantages in the application of in situ chemical oxidation (ISCO). Developing efficient, cost effective and environmentally friendly catalysts for SPC activation plays the key role in promoting the development of SPC-based ISCO. Herein, the walnut shell biomass was combined with ferric nitrate for the catalytic synthesis of Fe3C@biochar composite (Fe3C@WSB), which demonstrated high efficiency in activating SPC for the removal of diclofenac (DCF). The Fe3C showed average crystallite size of 32.6 nm and the composite Fe3C@WSB demonstrated strong adsorptivity. The prepared Fe3C@WSB could activate both SPC and H2O2 with high efficiency at ca. pH 3 with extremely low leaching of iron, while in a weak acidic condition, higher efficiency of DCF removal was obtained in the Fe3C@WSB/SPC process than in the Fe3C@WSB/H2O2 process. Moreover, the Fe3C@WSB/SPC and Fe3C@WSB/H2O2 processes did not show significant differences when supplied with varying amounts of catalyst or oxidant, but the Fe3C@WSB/SPC process exhibited stronger capability in dealing with relatively highly concentrated DCF solution. Based on quenching experiments and electron spin resonance (ESR) analysis, heterogeneous activation of SPC was assumed as the dominant route for DCF degradation, and both the oxidation by radicals, including •OH, •O2− and CO3•−, combined with electron transfer pathway contributed to DCF degradation in the Fe3C@WSB/SPC process. The cycling experiment results also revealed the stability of Fe3C@WSB. This work may cast some light on the development of efficient catalysts for the activation of SPC.

Integrating environmental remediation with biodiesel production from toxic non-edible oil seeds (Croton bonplandianus) using a sustainable phyto-nano catalyst

In the current situation of the environmental uprising toxicology, rising global temperature, and energy-depleting urges to explore and discover more renewable and greener ecological-benefiting energy resources. Biobased renewable fuels generated by using waste products can help in waste management, climate change mitigation, and a low-carbon future. The main objective of this research is to produce environment-friendly and cost-effective biofuel. The potentiality of the novel, toxic, waste, and inedible feedstock Croton bonplandianus was evaluated for biodiesel synthesis through transesterification utilizing a Phyto-nano catalyst of potassium oxide prepared by Croton bonplandianus floral stalk's aqueous extract focusing on waste management. Phyto-nano catalyst characterization was done through innovative tools such as Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), Zeta Potential (ZP), X-Ray Diffraction (XRD), Fourier Transformed Infrared spectroscopy (FTIR), and Diffuse Reflectance Spectroscopy (DRS). The characterization results revealed that the potassium oxide phyto-nanocatalyst possesses an average nanoparticle size of 44.5 nm. This size is optimal for enhanced catalytic activity, indicating significant potential for efficient catalysis. The highest yield (94 %) of biodiesel was secured at optimized reaction conditions of catalyst quantity (0.50 wt%), reaction time (180 min), methanol: oil ratio (9:1), and reaction thermal point (70 °C). Transformation of triglycerides to methyl esters was confirmed by GC/MS, NMR, and FTIR techniques. A total of 21 methyl esters were observed in Croton bonplandianus biodiesel confirmed via GC/MS results. Evaluation of fuel properties was done and matched with international fuel standards. The conclusive remarks for the conducted research are that Croton bonplandianus has a high potential for biodiesel production by applying Phyto-nanocatalysts of potassium oxide while dealing with hazardous environmental conditions and waste management. Phyto nanocatalyst of potassium oxide can be reused and gives the same yield after several cycles of reusability, this reusability of heterogenous Phyto nanocatalyst can reduce to total cost of biodiesel production and can contribute towards circular economy.

Study of the Sodium Borohydride Hydrolysis Reaction's Performance via a Kaolin-Supported Co-Cr Bimetallic Catalyst

Hydrogen is an attractive source of energy because of its properties, which include superior quality, effectiveness, pureness, dependability, and sustainability. Technologies for producing and storing hydrogen are being developed in parallel with fuel cell development. Chemical storage of hydrogen in a metal hydride containing boron eliminates the problem of hydrogen transportation and storage. Through catalytic reactions, hydrogen stored in solid form in boron hydrides can be recovered. In this study, a nowel developed Co-Cr bimetallic catalyst supported by kaolin, a natural mineral, was synthesized to be used for hydrogen production by hydrolysis of sodium boron hydride. The structural characteristics of the produced Co-Cr@Kaolin catalyst were ascertained by EDX, FTIR, and SEM analyses. Next, the ideal conditions for the hydrolysis reaction of sodium borohydride (NaBH4) catalyzed by Co-Cr@Kaolin were examined. These included the concentration of the catalyst, the amount of support material (kaolin), the amount of catalyst, and the concentration of NaBH4. The optimal hydrolysis conditions were found to be 2.5% NaOH concentration, 40 mg of catalyst, and 2% NaBH4 concentration at 303 K. The maximum rate of hydrogen production was determined as 5007 ml g-1 min-1 under optimal conditions. After conducting hydrolysis operations at different temperatures to elucidate the reaction kinetics, it was found that the catalytic hydrolysis reaction was of the 0th order and that the reaction activation energy was 19.36 kJ mol-1. The hydrogen production rate obtained as a result of the hydrolysis reaction accompanied by a Co-Cr catalyst was determined as 3166 ml g-1 min-1. It is therefore established that supporting kaolin to Co-Cr catalyst enhances its efficacy.

Comparative study of photo catalytic activity of Tinospora Cordifolia derived nanoparticles for degradation of indigo carmine

Plant-mediated synthesis of nanoparticles has emerged as an important field in synthesis of nanoparticles (NPs) as fewer chemicals are being used, method is cost-effective and also fulfils principles of green chemistry. Due to the rapid growth of industries in recent times, there has been an increase in concentration of dyes in water, which causes problems and affects human and animal’s health. Moreover, nanoparticles has emerged as an effective solution for dye degradation due to their effective catalytic activity. In the current work, we carried out a comparative study on Tinospora Cordifolia, derived oxide nanoparticles for degrading Indigo Carmine. The characterization of formed particles have been done by techniques like XRD, SEM, FTIR and EDX. The effectiveness of the synthesized nanoparticles as photo catalyst in removing indigo carmine was assessed by emphasizing on important aspects such as amount of catalyst, concentration of dye, and the pH. The results showed SnO2 nanoparticles exhibited superior degrading activity compared to CuO. The optimal dose for SnO2 NPs was 0.25 g/L, while for CuO, it was 0.50 g/L. When pH was altered, it was observed that acidic environment exhibited superior breakdown ability. The optimal degradation capability was observed at dye concentration of 40 parts per million (ppm).

Thermal and catalytic pyrolysis of automotive plastic wastes to diesel range fuel

This study investigated the pyrolysis of automotive plastic wastes (APW) for the production of diesel-grade oil products using a modified calcium bentonite clay catalyst. The research aimed to optimize the process for maximum oil yield and diesel range organics yield. The APW was characterized by its chemical composition and physical properties and the optimal temperature and catalyst amount were determined for maximum oil yield and diesel range hydrocarbons. The results showed that the APW contained mixed Acrylonitrile Butadiene Styrene (ABS), High/Low Density Polyethylene (H/LDPE), Polypropylene (PP), Polystrene (PS) and fiberglass, with a large quantity of volatiles and ash. The average oil yield was higher in the catalytic process compared to that in the thermal process. Generally, higher temperature above 450 °C produced waxy oil, thus lower temperature favoured more Diesel Range Organics (DRO). Both processes yield similar yields of C8–C24 DRO, and in both cases, lower temperature favoured high yield of C8-C24 hydrocarbons. The catalyst significantly increased the yield of oil, but did not significantly increase C8–C24 DRO yield. The optimal conditions for a maximum oil yield of 78.6 % and DRO yield of 79.5 % was a temperature of 416 °C and 24.3 wt% clay. Thus, the modified calcium bentonite clay can be used to improve oil yield from pyrolysis of APW. The oil produced had properties such as calorific value (49.85 MJ/kg), flash point (113 °C) and total aromatics 3.55 area%, similar to those of commercial diesel, and comprised mostly of 2,4-Dimethyl-1-heptene (25.37 ± 2.01 %) of thermal and 2, 4 – Dimethyl – 1 – heptane (23.44 ± 2.42) in the catalytic process. The study suggests further research to explore different catalysts, maximization of both DRO and gasoline range organics, recover energy from residues, and conduct techno-economic assessments for plant-scale operations. Additionally, policies on the management of end-of-life vehicles should include provisions for stripping and segregation of plastic components by accredited providers for the purpose of plastics recycling.

Photo-assisted Fenton degradation of tetracycline hydrochloride with magnetic Fe3S4/CuS composite

In recent years, semiconductor materials have gradually become popular through photodegradation of organic pollutants, and the semiconductor materials Fe3S4 and CuS have their own shortcomings. To make both materials useful, Fe3S4/CuS composites were prepared by hydrothermal method and degradation experiments were carried out using tetracycline hydrochloride (TCH) as a simulated pollutant. The effects of factors such as the mass ratio of Fe3S4 to CuS, temperature, pH changes, the consume of H2O2, and the amount of catalyst added on the degradation of TCH were explored. At room temperature, the Fe3S4/CuS composites exhibit good Fenton degradation efficiency. The F1C1.5 composite (mass ratio of Fe3S4 to CuS is 1:1.5) achieved 74.60 % at pH 4.0 within one hour. Subsequently, the free radical capture experiments and metal leaching experiments were conducted, and it was found that the active substance h+ played a major role. At the same time, the F1C1.5 composite shows stability, allowing for a lower concentration of iron leaching and having high catalytic activity after 5 cycles. These degradation properties, together with the ease of fabrication of the catalyst, will facilitate the practical application of this system in the continuous removal of TCH.

Feasibility Study of Rubber Seeds from North Sumatra, Indonesia as Biodiesel Feedstock; Production and Characterization

Abstract There are 5.5 million tons of rubber seeds produced annually on the 3.6 million hectares of rubber plantations that are located in Indonesia. Based on current estimates, 2.4 million tons of biodiesel may be produced if the rubber seeds are utilized as the primary raw material. Rubber seeds are a product of rubber plantations that have not been exploited; to obtain them, there is no need for new land or planting new trees. Rubber seeds are also non-edible, so their use does not conflict with foodstuffs. The purpose of this study was to assess the feasibility of rubber seed as a raw material for biodiesel and to produce and characterise biodiesel from rubber seed. The rubber seeds that have been collected from smallholder plantations in the northern Sumatra region of Indonesia are peeled to separate them from the kernels. Rubber seed kernels are boiled for 4 hours to separate the sap. Kernels that have been boiled are drained and then dried in the sun for 2 days in sunny weather. Kernels that had been dried in the sun were pressed using a screw press, and crude rubber seed oil was obtained. This crude oil is produced into biodiesel through degumming, esterification, and trans-esterification stages. Biodiesel production was carried out with variations in the catalyst ratios of 0.25, 0.5, 0.75, and 1, variations in the ratio of oil/methanol (w/v) of 1:1.25, 1:1.5, 1:1.75 (g/ml), and 1:2, variations in temperature of 50 °C, 60 °C, 70 °C, and 80 °C, and reaction times of 70 minutes, 80 minutes, 90 minutes, and 100 minutes. For each of these variables, the yield of biodiesel produced was calculated. Then the resulting biodiesel is characterised by testing its psychochemical properties against ASTM standards, which include calorific value, oxidation stability, viscosity, density, acid content, cetane number, and flash point. In the experiment on the effect of the amount of catalyst, the largest yield of 85% was obtained when the catalyst ratio (%v/v) was 0.75; in the investigation of the effect of the molar ratio of oil and methanol, the largest yield of 88% was obtained at a ratio of 1.75; the maximum yield of 85% was also obtained at a reaction temperature of 60 °C and 89% at a reaction time of 100 minutes. Almost all of the properties meet ASTM standards, except for the acid value of 0.53 mg KOH/g, which is 0.03 mg KOH/g higher, whereas according to the ASTM D6751-D 664 standard, the maximum acid value is 0.5 mg KOH/g.

Green and economical transesterification of castor oil for biodiesel production via a novel bentonite based Li2SiO3-LiAlO2 composite: Process technology & production feasibility

In our work, a highly efficient Li2SiO3-LiAlO2 composite was designed via a simple solid-state reaction using bentonite as raw material and successfully applied to the transesterification of castor oil with methanol for biodiesel production. The preparation processes for the bentonite-based Li2SiO3-LiAlO2 composite (Li/Bent) were optimized, and the prepared Li/Bent catalyst was characterized using a variety of experimental techniques. The maximum oil conversion to biodiesel of 97.16% was obtained under reaction temperature of 65 °C, reaction time of 90min, catalyst amount of 4wt.%, and methanol/oil molar ratio of 15:1. The possible mechanisms of the reaction process were revealed. The preliminary analysis of technical feasibility for the production showed that Li/Bent composites catalyzed castor oil production of biodiesel had competitive advantages in terms of market demand, industrial policy, process technology, environmental impact and economic benefits. The high efficiency and good stability of the catalyst reflect the technical advantages of the process. According to the study of environmental factor and process mass index, the synthesis process of biodiesel generated low waste, which was a green and environment-friendly process. Finally, the economic evaluation showed that the biodiesel production from castor oil catalyzed by Li/Bent catalyst was a cost-effective and low risk process.

Facile Synthesis of Silver‐Exchanged Phosphotungstic Acid Immobilized on Sn‐Bi Bimetallic Metal–Organic Frameworks for Enhanced Esterification

ABSTRACTMetal–organic frameworks (MOFs) are ideal supports for the synthesis of porous composite catalysts. In the present study, Sn‐Bi bimetallic metal–organic frameworks (Sn‐Bi‐MOFs) supported silver‐doped phosphotungstic acid (AgPW) catalysts (AgPW@Sn‐Bi‐BDC and AgPW@Sn‐Bi‐BDC (NH2)) were successfully synthesized via a simple in situ impregnation method, which was subsequently applied to catalyze esterification for the production of biodiesel from oleic acid (OA). The physico‐chemical properties of the prepared composite catalysts underwent comprehensive analysis through XRD, FTIR, N2 physisorption, SEM, EDX, NH3‐TPD, Py‐FTIR, TG, and XPS techniques, confirming the successful impregnation of AgPW on the Sn‐Bi‐MOFs framework. Among the catalysts tested, AgPW@Sn‐Bi‐BDC (NH2) exhibited the better catalytic activity than that of Sn‐Bi‐BDC, Sn‐Bi‐BDC (NH2), and AgPW@Sn‐Bi‐BDC, reaching 91.6% of OA conversion with the methanol:OA molar ratio of 20:1 and the catalyst quantity of 0.2 g at 130°C for 4 h. The high activity of AgPW@Sn‐Bi‐BDC (NH2) is attributed to the available multiscale pore structure, high acidity, and the synergistic action of the Brønsted and Lewis acidic sites. Additionally, the esterification with AgPW@Sn‐Bi‐BDC (NH2) followed the first‐order reaction kinetic model, with an Ea of 34.5 kJ/mol. Moreover, the recyclability of the composites was also assessed, demonstrating sustained catalytic activity after four reuses. This approach showed a potential for sustainable and efficient energy production through bimetallic MOFs‐based composite catalysts.

Pristine and Nature‐Inspired Hematite (α‐Fe2O3) Nanoparticles and Search for their Photocatalytic Application

AbstractThe article describes synthesis of green‐mediated hematite nanoparticles (20–30 nm) using Polianthes tuberosa flower extract. Structural, microscopic, and magnetic studies confirm the synthesis of iron oxide nanoparticles of pure hematite phase. Spectroscopic techniques are employed to identify different electronic transitions and defect levels as well as to estimate the energy bandgap and Urbach energy. A correlation among the particle size, bandgap energy, and Urbach energy is noticed. These hematite nanoparticles act as visible light photocatalyst which degrade dye in aqueous medium without the addition of any additives. The catalyst particle size, catalyst quantity, pH of dye solution, and solution temperature have significant impact on the photodegradation process of dye molecules in aq. solution. All observations advocate that green synthesis of hematite nanoparticles with Polianthes tuberosa flower extract can significantly modulate their optical and photocatalytic properties. These materials may find potential uses in water splitting for hydrogen production and purification of water by removing organic pollutants. The study highlights that using commercially cheap starting materials and extract made from naturally available plant parts, materials having huge application potentials can be synthesized at low cost by the simple green synthesis approach.

MnO2 as efficient and robust catalyst for halogen-free synthesis of cyclic carbonate from CO2 and epoxides

Cyclic carbonate is an important fine chemical/intermediate and their synthesis from CO2 and epoxides is economical and green pathway, however, it is still a challenge to develop a efficient and robust catalyst for halogen-free synthesis of cyclic carbonate. Herein, we successfully prepared large-scale MnO2 catalysts by microfluidics method, and the MnO2 especially δ-MnO2 showed >99.9 % propylene carbonate yield under 393 K, 3 MPa CO2 and DMF solvent. Moreover, the initial TOF value over δ-MnO2 on the basis of total catalyst amount was 5.80 h−1, which was the maximum among all the reported heterogeneous metallic oxide catalysts for halogen-free synthesis of propylene carbonate from CO2 and epoxides, and the superior catalytic performance can be ascribed to the abundant moderate acidic–basic active sites on the δ-MnO2 surface and the synergistic effect of δ-MnO2 and DMF. Furthermore, the δ-MnO2 can be reused at least 4 times and exhibited wide substrate applicability.