Environmental Friendly Catalyst Research Articles

Green and sustainable synthesis of 3,4-Dihydropyrimidin-2(1H)-ones/thiones via the Biginelli reaction using L-arabinose as a renewable catalyst under solvent-free conditions

In the pursuit of sustainable methodologies in organic synthesis, the application of renewable and biodegradable catalysts has received significant attention. This work processes the synthesizing of 3,4-dihydropyrimidin-2(1H)-ones/thiones using L-arabinose, an environment-friendly catalyst via the Biginelli reaction in a solvent-free environment is reported herein. L-arabinose, a naturally occurring sugar, efficiently catalyzes the condensation reaction between β-ketoesters and aldehyde with urea or thiourea to form DHPMs with high yields and excellent atom economy. The reaction proceeds efficiently at mild temperatures, and the catalyst is easily regenerated, enabling multiple catalytic cycles. The use of L-arabinose avoids not only toxic solvents and metal catalysts but also processes green chemistry due to the exploitation of renewable resources. It is a significant step forward in the domain of sustainable catalysis and provides an environmentally benign and operationally simple procedure for the synthesis of DHPMs.

Conjugated carbon network mediated - Graphdiyne based Cu2MoS4 homojunction for enhanced charge transfer dynamics

The preparation of stable and environment-friendly catalysts with high photocatalytic performance is of practical significance for the application of photocatalytic hydrogen evolution technology. Graphdiyne has a unique sp and sp2 hybrid structure, making it a potential photocatalyst due to its high surface carrier mobility and porous network structure. In this study, a Cu2MoS4 homojunction composite catalyst with conjugated carbon networks as electron transport channels was prepared by in situ solvothermal growth. Graphdiyne provides an additional pathway for photogenerated electron transfer, improving the efficiency of the interface charge separation. Simultaneously, the built-in electric field at the interface of Cu2MoS4 provides a strong driving force for electron transfer. Owing to the significant visible light absorption and effective multichannel transmission of photogenerated electrons, the Cu2MoS4/graphdiyne composite catalyst exhibited astonishing photocatalytic hydrogen evolution activity (11000 μmol g-1), which is 10 times that of Cu2MoS4 homojunction. Further experimental research and theoretical calculations provided effective evidence for the charge transfer pathway. This work provides a new strategy for constructing efficient hydrogen evolution photocatalysts and regulating the migration of photogenerated electrons.

Conversion of CO2 to cyclic carbonates using metal- and halogen-free Lewis pairs

The development of efficient and environmentally-friendly catalysts for the catalytic conversion of carbon dioxide (CO2) has been extensively investigated over a prolonged period. In this work, we successfully performed a cycloaddition reaction between CO2 and epoxides using metal- and halogen-free Lewis pairs as catalysts. Mechanistic investigations have revealed that Lewis acid-base pairs (LPs), a combination of Lewis acids (LAs) and Lewis bases (LBs), act in concert to activate epoxide and CO2, resulting in the efficient synthesis of various cyclic carbonates with high yields. Various epoxides are converted into cyclic carbonates with yields as high as 99% under cocatalyst-free and solvent-free conditions. Moreover, this homogeneous Lewis pair was incorporated into hypercrosslinked polymers through the Friedel-Crafts reaction, enabling the convenient recovery and reuse of the catalysts.

Na2S2O3 Catalyzed Three-Component Synthesis and Anti-Bacterial Activity of 3-Methyl-4-(hetero)arylmethylene isoxazole-5(4H)-ones.

An efficient and green method for synthesizing 3-methyl-4-(hetero) arylmethylene isoxazole-5(4H)-ones was developed using a recyclable and environmental-friendly catalyst, Na2S2O3, and 16 target compounds were successfully synthesized under the obtained optimal reaction condition. Using rifampicin as a positive control, the antibacterial activity of all synthesized compounds was tested by micro dilution method, among them, 3-methyl-4-[(2,4-dimethoxyphenyl) methylene]-isoxazole-5-one (4 m) presented wonderful antimicrobial activity, which may contribute to the development of anti-tuberculosis drugs.

Ofloxacin degradation in peroxymonosulfate system by Co/Fe bimetal-doped carbon nitride with pyridine nitrogen regulation

A bimetallic cobalt-iron supported graphite carbon nitride (CoFe/NC) was prepared via simple calcination method and used as a persulfate (PMS) activator for the removal of ofloxacin (OFL). The catalytic activity was regulated by pyrolysis temperature and nitrogen species in this activator. The characterization results proved that the material has the characteristics of ultra-low metal load and highly dispersed atoms. The OFL degradation efficiency of PMS activated by activators prepared at different pyrolysis temperatures (500 ℃/700 ℃/900 ℃) was compared. The results showed that the activator CoFe/NC-900 obtained by pyrolysis at 900 ℃ has the best removal efficiency (86%). Metal-pyridine N-site binding, hydroxyl group and electron transfer are the main mechanisms of OFL degradation in the CoFe/NC-900/PMS system. The reactive species responsible for the degradation of OFL were SO4• and •OH. Pollutant intermediates generated during pollutant disposal were detected by HPLC-MS and possible degradation pathways were proposed. Furthermore, the CoFe/NC-900 has good activation properties in different water bodies, and still achieves high performance after five cycles of utilization. This work will benefit the development of environmental friendly catalysts with low metal content and provide new strategies for environmental remediation.

Photocatalytic and adsorption behavior of a new efficient LaxNiyMn3–(x+y)O4/SiO2 composite for environmental remediation application

Environmental remediation of organic contaminants has recently received significant attention, necessitating the development of energy-efficient, cost effective, and environment-friendly catalysts. In this study, novel dual-doped LaxNiyMn3–(x+y)O4 nanoparticles (NPs) and their composite with an adsorptive material (mesoporous silica) were synthesized using a low-cost, environment-friendly coprecipitation technique. The as-prepared LaxNiyMn3–(x+y)O4 NPs and their composite were studied via X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), Fourier-transform infrared (FTIR) spectroscopy, and ultraviolet–visible spectroscopy. XRD analysis revealed that the LaxNiyMn3–(x+y)O4 NPs possessed a crystalline structure. FESEM showed that LaxNiyMn3–(x+y)O4 NPs were spherical with diameters ranging from 60 to 100 nm. The presence of metal–oxygen bonds in the LaxNiyMn3–(x+y)O4 NPs was confirmed by FTIR analysis. The LaxNiyMn3–(x+y)O4 NPs could degrade crystal violet (CV) dye under visible light with a percentage degradation of 82%, which increased to 92% with the addition of 0.5 mL of 6% H2O2 solution. Furthermore, to increase the adsorption ability of the LaxNiyMn3–(x+y)O4 NPs, a composite LaxNiyMn3–(x+y)O4/SiO2 was synthesized. Under dark conditions, the adsorption percentage of the LaxNiyMn3–(x+y)O4 NPs was 58%, whereas that of LaxNiyMn3–(x+y)O4/SiO2 reached 73%. The adsorption process was further explored using adsorption isotherms and reaction kinetic models. The central composite rotatable design of response surface methodology was used to statistically maximize the adsorption of CV by optimizing factors such as time (40 min), pH (8.68), and composite dose (12 mg). The prominent diffraction peak in the XRD pattern and the large surface area (532 m2/g) determined via Brunauer–Emmett–Teller analysis of the composite confirmed its unique porous characteristics, illustrating its high capacity for adsorbing pollutants inside the porous network. Studies on the degradation efficiency and adsorption–photocatalysis synergy suggest the substantial potential of the synthesized composite for application in environmental remediation.

Activation of persulfate by magnetic Mg/Mn–layered double oxide–doped biochar composite for ciprofloxacin removal and bacterial inactivation

Removal of antibiotics and bacteria from wastewater is an effective approach to test the efficacy of catalyst and thus address the issues of water contamination. In this study, a stable magnetic Mg/Mn–layered double oxide–doped biochar composite (MgMnLDO–MBC) was prepared using Lentinula edodes substrate. This composite could further effectively activate the persulfates (PS), such as peroxymonosulfate (PMS) and peroxydisulfate (PDS). MgMnLDO coupling endowed BC and magnetic biochar (MBC) with enhanced surface areas, adsorption sites, and free radicals, which facilitated the improvement of catalytic activity of MgMnLDO–MBC/PS system toward pollutants. MgMnLDO-MBC/PMS system could remove 90.8% of ciprofloxacin (CIP) with 2.8 times the removal efficiency of MBC/PMS system. Density functional theory (DFT) calculation and intermediate analysis showed that the synergistic effect of nucleophilic, electrophilic, and radical active species–mediated reactions improved the removal performance of MgMnLDO–MBC/PMS system. MgMnLDO–MBC/PDS system could efficiently kill 97.6% Escherichia coli and 99.7% Staphylococcus aureus, and destroy the existing biofilms. The effects of composite concentration, PMS loading, pH, temperature, common anions, and humic acid on removal efficiency were also evaluated. After five consecutive cycles, MgMnLDO–MBC/PS system still exhibited high catalytic performance toward CIP removal and bactericidal ability. Results of quenching and electron spin resonance (ESR) showed that ·SO, ·OH, 1O2, and charge transfer were together involved in CIP removal, with ·SO playing a major role. Furthermore, the double–layered metal oxide (LDO) and MBC present in MgMnLDO–MBC composites exhibited a strong synergistic effect in the catalytic process, which resulted in higher reactivity and lower leaching rate of metal ions. In this study, an environment–friendly catalyst was prepared using industrial waste and its efficiency for removal of antibiotics and bacteria from wastewater was verified.

Unprecedented Activation of CO2 by α-Amino Boronic Acids.

Efficient and environmentally benign transformation of carbon dioxide (CO2) into valuable chemicals is mainly obstructed by the lack of suitable catalysts. To date, various catalysts have already been investigated for the conversion of CO2 molecules, but still finding metal-free, simple, and environment-friendly catalysts is a topic of utmost interest among researchers. Thus, in this regard, the present work projects α-amino boronic acids (AABs) as a metal-free and simple catalyst for CO2 activation. The density functional theory (DFT)-based calculations have been carried out to explore the catalytic potential of AABs. The detailed electronic structure analysis of the considered AABs unveils the catalytic similarities with frustrated Lewis pairs (FLPs) in a gas phase. Interestingly, a peculiar catalytic action of AABs has been observed in the presence of solvents. The contrasting catalytic behavior of AABs in solvents has been extensively investigated by employing principal interacting orbital (PIO), intrinsic bond orbital (IBO), and natural bond orbital (NBO) analyses along the reaction paths. The results of the orbital studies provide concrete ground for the observed reaction mechanism. Further, the energetic analysis of the reaction of CO2 with AABs reveals that <5 kcal/mol energy is required for activation in a solvent phase, and the formed adducts are readily active. These observations show that AABs can be considered as an efficient catalyst for CO2 activation.

Combined immobilized lipases for effective biodiesel production from spent coffee grounds

This work describes the enzymatic transesterification of the oil extracted from SCGs for synthesis of biodiesel as a promising alternative to diesel fuels based on petroleum. Biocatalysts from various sources were tested for biodiesel synthesis using coffee oil among which CaCO3- immobilized Staphylococcus aureus and Bacillus stearothermophilus showed the highest conversion yields (61 ± 2.64% and 64.3 ± 1.53%, respectively) in 4 h. In further optimizing reaction parameters, methanol to oil molar ratio, biocatalyst quantity, water content, as well as incubation time and temperature markedly improved oil-to-biodiesel conversion up to 99.33 ± 0.57 % in a solvent free reaction after 12 h at 55 °C. A mixture of inexpensive CaCO3-immobilized bacterial lipases at a 1:1 ratio was the best environment-friendly catalyst for biofuel synthesis as well as the ideal trade-off between conversion and cost. Obtained coffee biodiesel remained stable beyond 40 days at ambient storage conditions and its chemical characteristics were comparable to those of other known biodiesels according to the European requirements (EN14214). Collectively, SCGs, after oil extraction, could be an ideal substrate for the production of an environment-friendly biodiesel by using appropriate mixture of CaCO3-immobilized lipases.

Retracted: Preparation of Ti Material Supported SBA-15 Functionalized with Sulfonic Acid Environmental Friendly Catalyst: Application for Esterification Process

Retracted: Preparation of Ti Material Supported SBA-15 Functionalized with Sulfonic Acid Environmental Friendly Catalyst: Application for Esterification Process

Multiaperture g-C3N4@SiO2 to activate peroxydisulfate via visible light for efficient Rhodamine B removal.

The sulfate radical-based advanced oxidation process (SR-AOPs) has been verified as a promising method tohandle the persistent organic compounds in water using peroxydisulfate (PDS) as oxidant. A Fenton-like process was constructed and showed great potential to remove organic pollutants using visible-light-assisted PDS activation. The g-C3N4@SiO2 was synthesized via thermo-polymerization, and characterized using powder X-ray diffraction (XRD), scanning electron microscope equipped with an energy-dispersive X-ray (SEM-EDX), X-ray photoelectron spectroscopy (XPS), N2 adsorption-desorption, Brunauer-Emmett-Teller (BET) and Barrett-Joyner-Halenda (BJH) method, photoluminescence (PL), transient photocurrent, and electrochemical impedance. Photocatalytic performance was demonstrated using the removal rate of Rhodamine B (RhB), and 96.08% RhB was removed from the solution within 50 min (10 mg/L in 200 mL, g-C3N4@SiO2 = 0.25 g/L, pH = 6.3, PDS = 1 mmol/L). The free radical capture experiment proved that HO•,h+,[Formula: see text] and [Formula: see text] were generated and removed RhB. The cyclic stability of g-C3N4@SiO2 has also been studied, and the result shows no noticeable difference in the six cycles. The system of visible-light-assisted PDS activation might provide a novel strategy for wastewater treatment and must be an environment-friendly catalyst.

Degradation bensulfuron-methyl by magnetic CoFe alloy@N-doped graphitized carbon derived from CoFe2O4 activated by peroxymonosulfate

Magnetic CoFe alloy@N-doped graphitized carbon nano-catalyst (CoFe@N-GC) was synthesized by hydrothermal method and chemical deposition method, which could couple with peroxymonosulfate (PMS) to degrade herbicide bensulfuron-methyl (BSM). CoFe alloy nanoparticles were encapsulated in N-doped graphitized carbon yarn-like material, providing strong stability and high corrosion resistance properties of them. Furthermore, CoFe alloy can make great improvement of degradation performance via tuning metal site’s intrinsic performance of the Fermi energy level density of states. CoFe@N-GC (k = 0.4 min−1) displayed better catalytic performance than CoFe2O4 (k = 0.14 min−1) because of the intrinsic strengths of each component, synergy between cobalt and iron, doping of nitrogen atoms and graphitized carbon and unique electronic properties. 10 mg·L−1 bensulfuron-methyl was degraded completely by the combination of CoFe@N-GC and PMS within 10 min at pH 7. Magnetic CoFe@N-GC could be separated from solution by an external magnet, thus making convenience to collect catalyst and avoiding second pollution. After 15 recycling use of CoFe@N-GC, the BSM degradation efficiency could still be maintained at 95%. CoFe@N-GC/PMS system exhibited stable degradation ability over a wide pH range (3–8) and displayed strong tolerance to real water samples. The main active species, possible BSM degradation pathways and potential reaction mechanism of CoFe@N-GC/PMS were systematically explored. Thus, our finding can provide an environmental friendly, efficient and easy recycle catalyst to degrade refractory organic matters by PMS activation.

Efficient electrocatalytic properties of transition metal (Mn, Co, Cu) doped LaFeO3 for ammonia synthesis via nitrate reduction

Electrochemical reduction of nitrate in wastewater to synthesize high-value energy, ammonia, is a promising technology to deal with the energy crisis and environmental pollution. It is an urgent task for this technology to find efficient, stable and environmental-friendly catalysts. This work innovatively applied transition metal (Mn, Co, Cu) doped LaFeO3 as the electrocatalyst to reduce nitrate to ammonia. Cu-doped LaFeO3 exhibited the optimum activity, achieving the ammonia yield of 1005.0 μg h−1cm−2 at − 1.1 V (vs. RHE) and the Faradaic efficiency of 71.9% at − 1.0 V (vs. RHE). The highly efficient electrocatalytic activity could be mainly attributed to the oxygen vacancies on the surface of the catalyst generated from Cu-doping. The oxygen atoms in the nitrate tended to fill in the oxygen vacancies, which promoted the adsorption of NO3- and weakened the N-O bonds. Besides, the oxygen vacancies and Cu sites could combine easily with the intermediate in the reaction, and their existence could also enhance the conductivity of the catalyst. Moreover, the catalyst showed outstanding stability and performed even enhanced activity during recycling, which was arised from the ferroelectricity of the catalyst. The ammonia yield was as high as 1250.5 μg h−1cm−2 in the third cycle, and the Faradaic efficiency was 74.5% in the fifth cycle at − 1.0 V (vs. RHE). This work presents a good paradigm of catalysts for the electrochemical synthesis of ammonia.

In situ doping lignin-derived carbon quantum dots on magnetic hydrotalcite for enhanced degradation of Congo Red over a wide pH range and simultaneous removal of heavy metal ions

A new N, S-CQDs@Fe3O4@HTC composite was prepared by loading N, S carbon quantum dots (N, S-CQDs) derived from lignin on magnetic hydrotalcite (HTC) via an in-situ growth method. The characterization results showed that the catalyst had a mesoporous structure. These pores facilitate the diffusion and mass transfer of pollutant molecules inside the catalyst, allowing them to approach the active site smoothly. The catalyst performed well in the UV degradation of Congo red (CR) over a wide pH range (3−11), with efficiencies over 95.43 % in all cases. Even at a high NaCl content (100 g/L), the catalyst showed extraordinary CR degradation (99.30 %). ESR analysis and free radical quenching experiments demonstrated that OH and O2− were the main active species governing CR degradation. Besides, the composite had outstanding removal efficiency for Cu2+ (99.90 %) and Cd2+ (85.08 %) simultaneously due to the electrostatic attraction between the HTC and metal ions. Moreover, the N, S-CQDs@Fe3O4@HTC had excellent stability and recyclability during five cycles, making it free of secondary contamination. This work provides a new environment-friendly catalyst for the simultaneous removal of multiple pollutants and a waste-to-waste strategy for the value-added utilization of lignin.

Singlet oxygen-dominated non-radical oxidation in biochar/peroxymonosulfate system for efficient degradation of tetracycline hydrochloride: Surface site and catalytic mechanism

BackgroundBiochar has attracted much attention in peroxymonosulfate (PMS) activation for the elimination of organic pollutants in water. However, the factor to determine the catalytic efficiency of biochar and the evolution of reactive oxygen species (ROS) remain equivocal and elusive. Method & resultIn this study, Camellia oleifera shell-derived biochar (COSB) was prepared by one-step pyrolysis. The pyrolysis temperature could tune the catalytic performance of COSB. Owing to more C=O groups and defects, the COSB-1000 prepared at 1000 °C showed the optimal activity in PMS activation. In the presence of 0.4 g∙L−1 of COSB-1000 and 1.0 g∙L−1 PMS, 91.57% of tetracycline hydrochloride (TC, 20 mg·L−1) was degraded within 105 min. In addition, the COSB-1000/PMS system demonstrated good anti-interference ability and a wide pH applicability from 3.0 to 11.0. Quenching experiment and electron spin resonance (EPR) spectroscopy suggested that the non-radical oxidation process dominated by the generated 1O2, which was converted from O2•−, play the vital role in TC degradation by the COSB-1000/PMS system. Furthermore, four possible degradation pathways of TC in the COSB-1000/PMS system are proposed by the mass spectroscopy, and the growth-inhibition of Escherichia coli showed that the degradation intermediates were low toxicity. Significant findingsThe results here shed light on the generation of 1O2 by biochar and deepen the insight for the environmentally-friendly catalysts derived from biomass in activating PMS for wastewater treatment.

Catalytic oxidation activation of peroxymonosulfate over Fe-Co bimetallic oxides for flurbiprofen degradation.

In this research, FeCo2O4 nanomaterial was successfully synthesized by a typical sol-gel method and conducted as an effective agent for peroxymonosulfate (PMS) activation to eliminate antibiotics flurbiprofen (FLU), a strong nonsteroidal drug. FeCo2O4 nanomaterial was characterized by XRD, TEM, SEM, and XPS. Various characterization results proved that FeCo2O4 held stable spinel structure. The interfering factors including initial pH, PMS concentration, catalyst dosage, inorganic anions, and humic acid on FLU removal were also discussed. The conclusion was that the removal efficiency of FLU reached 98.2% within 120min after adding FeCo2O4 (0.4gL-1) and PMS (3mM). The optimal pH for FLU degradation was the initial pH of 6.5; too acidic or alkaline was not conductive to the degradation. The existence of HA and Cl- restrained the degradation of FLU, and HCO3- promoted the removal, while the influence of NO3- and SO42- could not be considered. The radical scavenging experiment confirmed that •OH, O2•-, and SO4•- participated in FLU removal and SO4•- functioned a leading role. FeCo2O4 showed high efficiency for PMS activation in pH range of 3.0 to 10.0. After the fourth cycle operation, the FLU removal rate exceeded 76.9%, and the Co leaching rate was low during the catalytic reaction. This study shows that FeCo2O4 nanomaterial is an efficient and environment-friendly catalyst, which can be applied for PMS activation to remove organic pollutants in water.

Fibrous cellulose nanoarchitectonics on N-doped Carbon-based Metal-Free catalytic nanofilter for highly efficient advanced oxidation process

N-doped carbon materials have been considered as promising efficient and environment-friendly catalysts for sulfate radical-based advanced oxidation processes (SR-AOPs). Herein, we first report a facile strategy to prepare nanoporous N-doped carbon nanofilters (NCNFs) using cellulose nanofibers (CNFs) and metal–organic framework (MOF) as the superior metal-free catalytic for SR-AOPs. In this work, CNFs are employed as nanoporous templates and binders to fix ZIF-8 for fabricating ZIF-8@CNF membrane, and the as-prepared membrane was converted into NCNFs by a simple pyrolysis process. To evaluate the catalytic degradation performance of the NCNFs, methylene blue (MB) was chosen as a model contaminant. It is found that the NCNFs demonstrate a remarkable efficiency for MB removal by peroxymonosulfate (PMS) activation, and 96 % of MB (10 mg/L) was degraded in 15 min. The catalytic reaction and process including removal and washing are very simple and easy because the nanoporous N-doped carbons are fixed on CNF-derived networks. Furthermore, the reaction parameters including reaction temperature, pH, and catalyst/PMS dosage are also investigated. In addition, a series of radical quenching experiments reveal that non-radical mechanism is responsible for the degradation of MB. Importantly, the NCNFs membrane showed a good reusability by the annealing process and it can serve as a catalytic filter in practical organic dye remediation application. This present work shows that MOF derived metal-free carbon membranes have a promising avenue as catalysts for organic dye degradation and water remediation.

The catalytic characteristics of 2-methylnaphthalene acylation with AlCl3 immobilized on Hβ as Lewis acid catalyst

Abstract The heterogeneous supported Lewis acid catalyst prepared by immobilization technology has high reaction activity. It is an environment-friendly catalyst. Using Lewis acid immobilized as the catalyst, 2-methyl-6-propionyl naphthalene is synthesized by Friedel–Crafts reaction with 2-methylnaphthalene and propionic anhydride, which has a good development prospect. A variety of AlCl3 catalysts supported by H-zeolite molecular sieves are prepared using the solvent reflux method in the paper. It is found that AlCl3/Hβ has better catalytic performance. The results showed that AlCl3/Hβ catalyst is mainly composed of L acid. The acid content of B acid and the specific surface area increase, and the pore volume and pore size decreases. With the increase in AlCl3 concentration, the acid content of strong acid, medium strong acid, and weak acid increases, but the solubility of AlCl3 in CHCl3 is limited. When the concentration of AlCl3 is too high, too much AlCl3 is deposited on the surface of the molecular sieve, which is useless to its binding with Si–OH. AlCl3/Hβ’s activity is higher when the concentration of AlCl3 is 3 g·L−1, and the solvent is refluxed for 8 h and calcined at 550°C for 3 h. Under these conditions, the conversion of 2-methylnaphthalene is 85.86%, and the yield of β,β-methyl propyl naphthalene is increased to 81.19%.

Organic-Exchanged Silicotungstic Acid Compounds as Efficient and Environmental-Friendly Catalysts for Synthesis of Glycerol Monolaurate

A series of organic-exchanged silicotungstic acid catalysts were synthesized by changing the variety and amount of organic compounds. The structure, thermal stability and acidic properties of the catalysts were characterized by FT-IR, XRD, TGA and 31P-MAS NMR. The catalytic performances of the catalysts were investigated on the selective esterification of lauric acid with glycerol to glycerol monolaurate. Among the various catalysts, [QuH]1H3SiW12O40 with molar ratio of quinoline to silicotungstic acid of 1:1 showed excellent activity and reusability due to strong Brand#248;nsted acidity and “pseudo-liquid” catalytic modes. The optimal conditions optimized by response surface methodology were as follows: the molar ratio of glycerol to lauric acid was 5.3:1, the amount of catalyst was 4.8 wt%, the reaction temperature was 424 K, and the reaction time was 1.5 h. Under these conditions, the average yield of glycerol monolaurate was 79.7%, which was basically consistent with the values predicted by the mathematical model. Moreover, the kinetic data of this reaction were fitted to a second-order kinetic model and the apparent activation energy Ea was 52.35 kJ / mol

Synergistic effect of Pd-Co3O4 nanoparticles supported on coffee-derived sulfur, nitrogen-codoped hierarchical porous carbon for efficient methanolysis of NaBH4

Sulfur, nitrogen-codoped (SN-doped) highly porous carbon nanostructures (CNSs) are established as efficient components for hydrogen generation applications. Waste coffee grounds are carbonized in situ and activated with KOH to produce hierarchically SN doped porous carbon nanostructures with a large specific surface area of 2320 m2 g−1. The amorphous and highly active Pd-Co3O4 nanoparticles (NPs) are anchored onto an SN-codoped carbon nanosheet prepared via a simple hydrothermal reaction. An effective method for optimization of the Pd-Co3O4/SN-CNS-600 catalytic efficiency for NaBH4 methanolysis using sodium sulfide as a precursor or combination of sulfur-containing salts as a raw material is proposed. The Pd-Co3O4/SN-CNS-600 catalyst exhibits an excellent catalytic activity for NaBH4 catalytic methanolysis at room temperature, with a high hydrogen generation rate of 20158 mL H2 min−1 gcat−1. The methanolysis reaction activation energy in an aqueous NaBH4 solution is approximately 14.52 kJ/mol. The excellent Pd-Co3O4/SN-CNS-600 catalytic activity is attributed to the small size and amorphous state of Pd-Co3O4 NPs, good synergistic interaction between Pd-Co3O4 NPs and SN-CNS with a large specific surface area, and abundant defects. Highly efficient, inexpensive, and environment-friendly catalysts are successfully developed for hydrogen generation.