Activated Carbon Catalyst Research Articles

Continuous-flow degradation of Orange I using CoFe2O4-loaded activated carbon catalyst: Optimization of reaction parameters and toxicity prediction

Orange I (OI) azo dyes produce toxic aromatic compounds in water, making solutions an important issue. In this study, we employed the urea combustion method to load CoFe2O4 particles onto activated carbon (CFO-AC-500). Subsequently, the catalyst was incorporated into a column continuous flow device, testing the effects of multi water parameters and toxicity, and predicting the degradation process on the catalytic degradation of OI for peroxymonosulfate (PMS) activation. In CFO-AC-500/PMS continuous reactor, it showed a satisfied OI removal of more than 82 % of the OI at a flow rate of 73.6 mL/min in 240 min. Also, response surface methodology (RSM) was employed to optimize the operating conditions, with model fitting results demonstrating that the OI removal rate could reach 95.07 % under specific conditions. ESR analyses revealed that the degradation of OI was primarily governed by free radicals (SO4•-, HO• and O2•-) and non-radical pathways (1O2). The biological toxicity of degraded OI was significantly reduced. This innovative CFO-AC-500/PMS continuous flow system can provide an effective new method for the degradation of difficult-to-treat pollutants in practical applications.

Enhancing SO2 Resistance of Mn−Ce−Co Loaded Activated Carbon Catalysts for Low‐Temperature NH3‐SCR: Insight into the Effect of Citrate Addition

AbstractThe low‐temperature performance and ability to withstand SO2 poisoning of catalyst are crucial factors in evaluating the NH3‐SCR technology. In this study, honeycomb activated carbon loaded with Mn−Ce−Co catalysts was prepared using the citric acid complex impregnation method, simple impregnation and citric acid pre‐oxidation methods for low‐temperature NH3‐SCR. The synergistic effect of citric acid and ternary metals results in catalysts prepared by the citric acid complex impregnation method exhibiting excellent redox properties and a high abundance of acidic sites. By increasing catalyst acidity and introducing CeO2 sacrificial sites, the catalytic performance was improved, resulting in weaker adsorption capacity of the catalysts for SO2, enhancing SO2 tolerance. The catalyst demonstrated 100 % NOx removal at 160 °C which remained stable even after a 100 ppm SO2 pass for four hours. In addition, the catalyst showed good CO oxidation performance, with 78 % CO removal at 170 °C, which broadened the application scenario of the catalyst. This study highlights the denitrification effect of activated carbon supported Mn−Ce−Co ternary metal oxide catalysts and reveals the potential of multiple coupled approaches in improving the sulfur resistance of the catalysts.

Sustainable Heat Generation in Flow from a Molecular Solar Thermal Energy Storage System

As the global deployment of renewable technologies accelerate, finding efficient ways to store energy will aid in responding to shifting energy demands. A prospective option not only in harvesting solar energy but also in emission‐free heating is MOlecular Solar Thermal (MOST) energy storage. A central part of MOST applications is to develop methods to release the stored energy. Herein, the Quadricyclane (QC)‐to‐Norbornadiene catalyzed back reaction is explored in a specially designed packed‐bed reactor. Four distinctly sized and purposely synthesized platinum on activated carbon catalysts are studied to trigger the heat release from the energy‐dense QC isomer. The catalysts are fully characterized using a variety of structural, surface, and spectroscopic techniques. Parameters to optimize catalytic conversion and heat release in flow conditions are explored including particle size and packing behavior, flow rates, and molecular residence times. Moreover, using CO pulse chemisorption technique, site time yield values and a turnover number are reported. Complementary to the flow reactions, computational fluid dynamic simulations applying lattice Boltzmann methods to two catalytic packed beds of different size ranges are done to evaluate fluid‐dynamic behavior within the reactor bed to ascertain the ideal particle size and packing density for catalysis in MOST applications.

Catalytic conversion of biomass pyrolysis volatiles over composite catalysts of activated carbon and HY zeolite

Bio-oil has complex compositions and high oxygen content, which restricts its high-value utilization. Commercial activated carbon (AC) and HY zeolite were used as composite catalysts to study their effect on pyrolysis volatiles from rice straw and poplar sawdust by changing the mixing modes of two catalysts. The results showed that the loading modes of AC and HY zeolite obviously affected the products distribution and bio-oil components. The lowest yield of bio-oil was obtained when HY zeolite and AC were mechanically mixed at a mass ratio of 1:1 (YACM). But the loading mode of YACM was beneficial to the deoxidation and aromatic hydrocarbon generation. Under the mode of YACM, the aromatics content in rice straw and poplar sawdust bio-oil can be increased from 13.8% and 8.0% without catalyst to 56.4% and 53.1%, respectively. However, the layered loading with upper HY zeolite and lower AC (YTACL) was favorable for formation of phenolic compounds. The selectivity to monocyclic and bicyclic aromatic hydrocarbons followed the order of YTACL > ACTYL > YACM, and YACM > ACTYL > YTACL, respectively. Compared with HY zeolite, AC catalyst possessed smaller pore size and fewer acidity, and the active sites of AC were conducive to rearrangement of furan compounds to generate cyclopentanone, 2-cyclopentenone and methyl-cyclopentenone, and further rearrangement to form phenol. Therefore, the loading mode of YTACL exhibited a promotion effect on the formation of phenol, cresol, toluene, ethylbenzene and p-xylene. The strong acidic sites of HY zeolite were favorable for the aromatization, so the loading mode of ACTYL had good selectivity to the formation of naphthalene, methylnaphthalene, anthracene and pyrene. This work will provide a guide for products regulation from biomass pyrolysis and enrich aromatics and phenols in bio-oil.

Microwave pyrolysis of polypropylene, and high-density polyethylene, and catalytic gasification of waste coffee pods to hydrogen-rich gas

Plastic waste poses a critical environmental challenge for the world. The proliferation of waste plastic coffee pods exacerbates this issue. Traditional disposal methods such as incineration and landfills are environmentally unfriendly, necessitating the exploration of alternative management strategies. One promising avenue is the pyrolysis in-line reforming process, which converts plastic waste into hydrogen. However, traditional pyrolysis methods are costly due to inefficiencies and heat losses. To address this, for the first time, our study investigates the use of microwave to enhance the pyrolysis process. We explored microwave pyrolysis for polypropylene (PP), high-density polypropylene (HDPE), and waste coffee pods, with the latter primarily comprising polypropylene. Additionally, catalytic ex-situ pyrolysis of coffee pod pyrolysis over a nickel-based catalyst was investigated to convert the evolved gas into hydrogen. The single-stage microwave pyrolysis results revealed the highest gas yield at 500 °C for HDPE, and 41 % and 58 % (by mass) for waste coffee pods and polypropylene at 700 °C, respectively. Polypropylene exhibited the highest gaseous yield, suggesting its readiness for pyrolytic degradation. Waste coffee pods uniquely produced carbon dioxide and carbon monoxide gases because of the oxygen present in their structure. Catalytic reforming of evolved gas from waste coffee pods using a 5 % nickel loaded activated carbon catalyst, yielded 76 % (by volume) hydrogen at 900 °C. These observed results were supported by elemental balance analysis. These findings highlight that two-stage microwave and catalysis assisted pyrolysis could be a promising method for the efficient management of waste coffee pods, particularly for producing clean energy.

Catalytic Applications in the Production of Hydrotreated Vegetable Oil (HVO) as a Renewable Fuel: A Review

The significance and challenges of hydrotreatment processes for vegetable oils have recently become apparent, encompassing various reactions like decarbonylation, decarboxylation, and hydrogenation. Heterogeneous noble or transition metal catalysts play a crucial role in these reactions, offering high selectivity in removing oxygen and yielding desired hydrocarbons. Notably, both sulphided and non-sulphided catalysts exhibit effectiveness, with the latter gaining attention due to health and toxicity concerns associated with sulphiding agents. Nickel-based catalysts, such as NiP and NiC, demonstrate specific properties and tendencies in deoxygenation reactions, while palladium supported on activated carbon catalysts shows superior activity in hydrodeoxygenation. Comparisons between the performances of different catalysts in various hydrotreatment processes underscore the need for tailored approaches. Transition metal phosphides (TMP) emerge as promising catalysts due to their cost-effectiveness and environmental friendliness. Ultimately, there is an ongoing pursuit of efficient catalysts and the importance of further advancements in catalysis for the future of vegetable oil hydrotreatment.

A Spherical Superhydrophobic Activated Carbon Catalyst for Biodiesel Production ‐Exploring Process Efficiency, Kinetics, Thermodynamics and Life Cycle Cost Analysis

AbstractEngineering the wettability of functional materials holds significant interest, focusing on the need for superhydrophobic catalysts, crucial for their ability to prevent the poisoning of active sites by water, produced in situ or as a by‐product. Herein, for the first time, a superhydrophobic spherical activated carbon (SSAC@PhSO3H) is engineered as a catalyst via a novel synthetic approach and tailored in Jatropha curcas oil (JCO) biodiesel synthesis. With a large surface area (1461 m2 g−1), high acid density (6.26 mmol g−1), and water contact angle (163.4°), the catalyst demonstrates superior performance and remarkable water repellency, firmly establishing its superhydrophobic characteristics. Response Surface Methodology based on the Central Composite Design (RSM‐CCD) approach predicted a maximal biodiesel yield of 98.8% (80 °C, 5 wt%, 15:1 methanol to oil molar ratio (MOMR), and 40 min). Life cycle cost analysis (LCCA) estimates biodiesel production cost of 0.37 USD ($) per kg emphasizing high commercial viability. Compared with H2SO4‐sulfonated biochar, SSAC@PhSO3H retains its inherent activity (86.8 ± 0.4% yield in 10th run) and spherical morphology even after nine successive reaction cycles indicating high stability. Nevertheless, JCO biodiesel's fuel properties met European Norm, EN 14 212 and American Society for Testing and Materials, ASTM D6757 standards, highlighting its potential for industrial biodiesel production.

Efficient oxidation of monosaccharides to sugar acids under neutral condition in flow reactors with gold-supported activated carbon catalysts

Efficient oxidation of monosaccharides to sugar acids under neutral condition in flow reactors with gold-supported activated carbon catalysts

Response surface optimization, kinetics, thermodynamics, and life cycle cost analysis of biodiesel production from Jatropha curcas oil using biomass-based functional activated carbon catalyst

A highly efficient activated porous catalyst, BPAC-500-S, derived from waste banana peels through a novel synthesis involving pyrolysis; and functionalization with 4-benzene diazonium sulphonate, has been developed. For comparison of catalytic activity, the material was also functionalized with sulphuric acid (BPAC-500-SX). The (BPAC-500-S) catalyst underwent impregnation and activation with ZnCl2, and its properties were extensively characterized using BET, SEM, XPS, XRD, FT-IR, and TGA techniques. Comparative analysis of catalysts obtained at different pyrolysis temperatures (400, 500, and 600 °C) revealed that BPAC-500-S pyrolyzed at 500 °C, exhibited maximum surface area (840.83 m2g-1) and sulphur density (4.7 %). Utilizing BPAC-500-S as a catalyst, an efficient process for biodiesel synthesis from Jatropha curcas oil (JCO) was developed, achieving a remarkable 98.91 % conversion, as confirmed by 1H NMR spectroscopy. Notably, life cycle cost analysis demonstrated a low biodiesel production cost of $ 0.70/L. The BPAC-500-S catalyst exhibited exceptional reusability maintaining more than 80 % biodiesel yield over seven reaction cycles. This study presents a sustainable and cost-effective approach to biodiesel production, emphasizing the potential of waste-derived catalysts in green and economically viable processes.

Low-temperature activated porous carbon with functional groups derived from waste tea powder as a potential catalyst for CO2 fixation into cyclic carbonates

The globe is currently confronted with two main environmental problems: environmental solid waste and greenhouse gases. Thus, it is urgent to mitigate these issues and convert them into value-added products. In this context, this work demonstrated the mitigation of two global issues with a single approach. This work established a facile process for a hierarchical porous carbon from abundant bio-waste, such as waste tea powder, and employed it as a heterogeneous catalyst for CO2 fixation into cyclic carbonate. Derived porous carbon catalysts, WTC-1 (Waste tea carbon), WTC-2, AWTC-2-400 (Activated waste tea carbon), AWTC-2a-400, AWTC-2-600, and AWTC-2-800, were produced without the use of solvent by acid-free washing and KOH-free activation. These WTC catalysts were characterized by several standard techniques: XRD, FTIR, XPS, SEM, BET, and TPD. Among the low-temperature activated carbon catalysts, AWTC-2a-400 with potassium-based salt, KI exhibited excellent conversion of propylene oxide (98 %) and ≥99 % selectivity of propylene carbonate without solvent under mild conditions of 2.5 MPa, 120 °C, and 2 h. It was observed that the catalytic activity of the WTC catalyst was attributed to the presence of Lewis acidic and basic sites, CaO/CaCO3, MgO, –COOH/OH, and –NH, which are capable of activating the CO2 molecule. Further, the developed catalytic system (AWTC-2a-400/KI) demonstrated superior catalyst versatility for various epoxides under optimized conditions. Moreover, AWTC-2a-400 showed good stability and reusability. Importantly, all reactions were conducted on a gram scale, and the proposed catalyst was effective, which might be favorable for future industrial applications.

Efficient ozone decomposition in high humidity environments using novel iron-doped OMS-2-loaded activated carbon material.

This study effectively addresses the rapid deactivation of manganese-based catalysts in humid environments during ozone decomposition by introducing iron-doped manganese oxide octahedral molecular sieve (Fe-OMS-2) catalysts supported on activated carbon (AC). By optimizing the doping ratio of Fe-OMS-2, the Fe-OMS-20.5/AC catalyst achieves nearly 100% ozone decomposition efficiency across a wide range of relative humidity levels (0 to 60%), even at elevated air flow rates of 800 L·g-1·h-1, outperforming standalone AC, Fe-OMS-2, or a simple mixture of OMS-2 and AC. The Fe-OMS-20.5/AC catalyst features a porous surface and a mesoporous structure, providing a substantial specific surface area that facilitates the uniform distribution of the Fe-OMS-2 active phase on the AC surface. The incorporation of Fe3+ ions enhances electron transfer between valence state transitions of Mn, thereby improving the catalyst's efficiency in ozone decomposition. Additionally, the AC component protects catalytic sites and enhances the catalyst's humidity resistance. In conclusion, this research presents a novel strategy for developing highly efficient and cost-effective ozone decomposition catalysts that enhance dehumidification, significantly contributing to industrial ozone treatment technologies and advancing environmental protection.

Influence of nickel contents on synthesis gas production over nickel-based catalysts supported by treated activated carbon in dry reforming of methane

This study focuses on the utilization of activated carbon (AC) as a catalyst support after undergoing treatment with HNO3. The treated AC exhibited a microporous structure and a high specific surface area (SBET) of 1483.8 m2 g−1. In this study, supported nickel-based catalysts were synthesized using the wet impregnation method with varying amounts of NiO (2.5, 5, 7.5, 10, 12.5, and 15 wt%). The calcined catalyst samples were then evaluated for their performance in the dry reforming of methane (DRM). Characterization of the catalysts was conducted through FESEM, TPO, H2-TPR, XRD, and N2 adsorption-desorption (BET) analyses. The results revealed that catalytic efficiency increased with an increase in the nickel loading percentage, up to 12.5 wt%. The NiO (12.5)/AC catalyst demonstrated the highest CH4 (60%) and CO2 (68%) conversions and exhibited good stability at 700 °C during 10 h of reaction. Additionally, the catalyst's efficiency decreased with an increase in the calcination temperature from 400 to 600 °C. However, alterations in the CH4/CO2 molar ratio from 0.5 to 1.5 indicated that CH4 and CO2 conversions decreased from 85% to 40% and increased from 63% to 74% at 700 °C, respectively. Moreover, the findings demonstrated that elevating the gas hourly space velocity (GHSV) from 12,000 to 18,000 ml h−1.g−1cat resulted in a decline in catalytic efficiency at a temperature of 700 °C. Moreover, the catalytic efficiency declined with an increase in the reduction temperature from 500 to 600 °C.

Activated Carbon Anchoring Site Enrichment Through B and N Codoping for Boosting Bi2Mo2.5(S,O)10 Oxysulfide Catalyst Stability and Visible‐Light‐Driven Hydrogen Evolution

AbstractBoron and nitrogen can enter the carbon lattice and provide structural disorder, porous structure, and active sites for better catalyst dispersions and activity. Herein, Bi2Mo2.5(S,O)10 oxysulfide (BiMoOS) anchored on unmodified and surface‐modified activated carbon (AC) via B and N doping is synthesized for efficient PHER, aiming that B and N doping into carbon framework can modify the surface textural features which act as anchoring sites for the host Bi2Mo2.5(S,O)10 and boost its photocatalytic activity by increasing specific surface area via preventing aggregation through a uniform distribution. Thus, the BiMoOS@B─N─AC catalyst achieved excellent stability and PHER performance (564.2 µmol h−1 H2 under visible light). The doped B and N in AC create structural disorder/defects, active sites and induce electron delocalization in B─N─AC, used as the anchoring sites for BiMoOS catalysts and stimulate the adsorption and activation kinetics of the H2O molecules, and also provide a highly conductive network that enhances charge transport and stability of BiMoOS@B─N─AC. With the advantages of the modified B─N─AC, the oxygen vacancy‐anchored BiMoOS exhibited superb PHER. Hence, B and N co‐doping into the carbon lattice is a promising approach to enriching the anchoring site for boosting metallic nanocatalyst stability and catalytic performance.

Manufacturing the activated carbon catalyst of impregnated palm core shells for biodiesel production

This research aims to produce activated carbon-based heterogeneous catalyst derived from palm kernel shells impregnated with a KOH solution and to determine the effects of the concentration of the KOH solution and the time period during impregnation. The variables observed included KOH concentration and impregnation time. The impregnation process used KOH solution with the solution concentrations of 1N, 2N, 3N, 4N and 5N with impregnation process within 18 hours, 21 hours and 24 hours. AAS, FTIR and SEM were analyzed after impregnation with different concentrations and times. The results of the analysis of potassium metal showed the highest absorption occurred at a concentration of 5N within 21 hours at 25.4570%. The application of the activated carbon catalyst from palm kernel shells was conducted in making biodiesel. The process of making biodiesel was carried out with a reaction time of 120 minutes at a temperature of 60℃ with a molar ratio of 1: 12 using a catalyst of 2% (% w/w). Biodiesel yield testing referred to SNI 04-7182-2015. The analysis results obtained showed 879 kg/m3 density, 6.1 cst viscosity, 0.5 acid number, and 174℃ flash point.

Continuous kinetics of 2-hydroxyisobutryic acid esterification using solid acid granular and monolithic activated carbon catalysts

Kinetics of 2-hydroxyisobutyric acid (2-HIBA) esterification with ethanol was studied using sulfonated carbon catalysts in granular (sGAC) and monolith (sACM) forms in a continuous flow packed bed reactor. 2-HIBA is a potential biobased carboxylic acid and its ester a sustainably produced industrial solvent. The catalyst monolith form, made from renewable carbon, offers significantly higher space time yields and conversions, yet little kinetic data or models are available for its use, especially under non-ideal conditions. The effect of ethanol/2-HIBA molar ratio (44, 10, 3.6 and 1.5) at different liquid residence times (3–9 min) was investigated using sGAC. Kinetics of sACM esterifications were investigated at a molar ratio of 3.6 by varying the residence time (2–7 min) and compared with the sGAC. The sACM displayed higher ester yields, acid conversions, and significantly higher reaction rates and space–time-yields (2.1–2.8 ×) compared to the sGAC due to higher surface area to volume ratio. The sACM reaction rates and turnover frequency were comparable to solid acid resins and sulfated silica and zirconia. Pseudo-homogeneous, Eley-Rideal and Langmuir-Hinshelwood models were applied to fit the kinetic data, and the reaction system parameters were obtained through regression analysis. The LH dual active site model resulted in the lowest mean relative error for both 2-HIBA and ester concentration residuals. Adsorption/desorption equilibrium constants for 2-HIBA, ethanol, and ester, were higher compared to water suggesting hydrophobic regions in the sGAC/sACM. Estimation of the external and internal mass transfer criteria indicated negligible effects of mass transfer. With further development sACM and the kinetic model can be used for reactor design of continuous esterification processes using solid acid monolith catalysts.

Metronidazole degradation mechanism by sono-photo-Fenton processes using a spinel ferrite cobalt on activated carbon catalyst

A heterogeneous catalyst was prepared by anchoring spinel cobalt ferrite nanoparticles on porous activated carbon (SCF@AC). The catalyst was tested to activate hydrogen peroxide (HP) in the Fenton degradation of metronidazole (MTZ). SCF nanoparticles were produced through the co-precipitation of iron and cobalt metal salts in an alkaline condition. Elemental mapping, physico-chemical, morphological, structural, and magnetic properties of the as-fabricated catalyst were analyzed utilizing EDX mapping, FESEM-EDS, TEM, BET, XRD, and VSM techniques. The porous structure of AC enhanced the catalytic activity of SCF by a significant decrease in the agglomeration of SCF nanoparticles. The effectiveness of SCF@AC in Fenton degradation improved substantially when UV light and ultrasound (US) irradiations were induced, most likely due to the strong synergistic effect between the catalyst and these irradiation sources. The photo-Fenton system was more efficient than the Fenton, sono-, and sono-photo-Fenton processes eliminating both MTZ and TOC. It was found that AC not only dispersed SCF nanoparticles and improved the stability of the catalyst, but also provided a high adsorption capacity of MTZ, resulting in a faster degradation. After 60 min of the photo-Fenton reaction, the elimination efficiencies of MTZ (30 mg L−1) and TOC were 97 and 42.1% under optimum operational conditions (pH = 3.0, HP = 4.0 mM, SCF@AC = 0.3 g L−1, and UV = 6 W). SCF@AC showed excellent stability with low leaching of metal ions during the reaction. Radical and non-radical (O2•–, HO•, and 1O2 species), alongside adsorption and photocatalysis mechanisms, were responsible for MTZ decontamination over the SCF@AC/HP/UV system. A comprehensive study on the HP activation mechanism and MTZ degradation pathway was obtained through scavenging tests. The findings demonstrate that SCF@AC is an effective, reusable, and environmentally sustainable catalyst for advanced oxidation processes that can effectively remove organic pollutants from wastewater. This study offers valuable insights into the feasibility of employing SCF@AC catalysts in Fenton-based processes for the degradation of MTZ.

Deoxygenation of waste sludge palm oil into hydrocarbon rich fuel over carbon-supported bimetallic tungsten-lanthanum catalyst

Activated carbon (AC) supported catalysts have been extensively applied as deoxygenation (DO) catalysts. However, the details of in situ experimental investigations that relevant to this catalyst are limited. Hereby, we present a series of operando/in situ spectroscopic experiments for DO of waste sludge palm oil (WSPO) by using atomically dispersed La-W bimetallic supported AC catalysts (La-W/AC) with well-defined structures. The La(5%)-W(2%)/AC catalyst prepared through co-precipitation (CP) process rendered high surface area (741 m2/g) and catalyst’s acidity (13319.16 µmol/g). Besides, the catalyst demonstrated a superior catalytic performance of DO reactivity under optimal reaction conditions of 0.5 % catalyst loading (CL), a one hour reaction time (Rt), and 250 °C reaction temperature (RT), achieving 98 % WSPO conversion to green fuel turnover frequency (TOF) of 0.0153 s-1. The reusability of La(5%)-W(2%)/AC catalyst was positively active for eight runs of DO process with constant of conversion rate at > 87 %. In addition, DO mechanism was of WSPO model compound (palmitic acid) was conducted to gain the clearer insight of reaction pathway catalysed by La-W/C catalyst. In situ FTIR analysis confirms the presence of intermediates (e.g. n-heptadecane, n-pentadecane, n-nonane, n-tridecane, and trimethylcyclopentene) that attributed buy the acid site of the heteropoly acid support. Besides, in situ XAS spectroscopy consolidates the oxidation state of La and W, where the presence of metal centre, support and substrate were confirmed to reflect the occurrence of palmitic acid DO on atomically dispersed La and W active sites. Thus, the present findings identified several key product intermediates during DO process, as well as the stable-state of catalyst structure, which suggest that the atomically dispersed La(5%)-W(2%)/AC catalysed reactions follow an unconventional decarboxylation/decarbonylation reaction pathways with the activation of oxygen (O2) removing is rate limiting.

Catalytically Active Carbon for Oxygen Reduction Reaction in Energy Conversion: Recent Advances and Future Perspectives.

The shortage and unevenness of fossil energy sources are affecting the development and progress of human civilization. The technology of efficiently converting material resources into energy for utilization and storage is attracting the attention of researchers. Environmentally friendly biomass materials are a treasure to drive the development of new-generation energy sources. Electrochemical theory is used to efficiently convert the chemical energy of chemical substances into electrical energy. In recent years, significant progress has been made in the development of green and economical electrocatalysts for oxygen reduction reaction (ORR). Although many reviews have been reported around the application of biomass-derived catalytically active carbon (CAC) catalysts in ORR, these reviews have only selected a single/partial topic (including synthesis and preparation of catalysts from different sources, structural optimization, or performance enhancement methods based on CAC catalysts, and application of biomass-derived CACs) for discussion. There is no review that systematically addresses the latest progress in the synthesis, performance enhancement, and applications related to biomass-derived CAC-based oxygen reduction electrocatalysts synchronously. This review fills the gap by providing a timely and comprehensive review and summary from the following sections: the exposition of the basic catalytic principles of ORR, the summary of the chemical composition and structural properties of various types of biomass, the analysis of traditional and the latest popular biomass-derived CAC synthesis methods and optimization strategies, and the summary of the practical applications of biomass-derived CAC-based oxidative reduction electrocatalysts. This review provides a comprehensive summary of the latest advances to provide research directions and design ideas for the development of catalyst synthesis/optimization and contributes to the industrialization of biomass-derived CAC electrocatalysis and electric energy storage.

Biobased Vanillin Production by Oxidative Depolymerization of Kraft Lignin on a Nitrogen- and Phosphorus-Functionalized Activated Carbon Catalyst

Biobased Vanillin Production by Oxidative Depolymerization of Kraft Lignin on a Nitrogen- and Phosphorus-Functionalized Activated Carbon Catalyst

Kapok Derived Activated Carbon Catalyst Assisted in Biodiesel Production from Waste Cooking Oil

The present study aims to synthesize green carbon-based catalyst from kapok (Ceiba pentandra) using two different activating agents: KOH (CB1) and K2CO3 (CB2) with 1:1.0 (raw material: activating agent), at activation temperature of 400 °C and impregnation time of only 15 min. The synthesized catalysts were evaluated in the transesterification of waste cooking oil (WCO) into biodiesel. CB1 registered higher iodine number and percentage yield (1446.30 mg/g, 62.60 %) compared to 1200.23 mg/g and 53.50 % obtained for CB2. Several physico-chemical characterizations were subjected for kapok and the carbon catalysts such as Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscope (SEM) and CHNS/O Analyzer. FTIR investigation showed the disappearance or reduction in peak intensity of several peaks at 1512-1200 cm-1 in the carbon catalyst compared to raw kapok, arising due to carbonization and activation processes. CHNSO analysis verified that both CB1 and CB2 registered high carbon content of 63.93 % and 62.86 %, respectively compared to the raw kapok (43.54 %). Morphological studies by SEM analysis showed appearance of cylindrical tube for all the samples. The biodiesel synthesis from WCO at 0.2 wt.% catalyst loading, methanol to oil (molar ratio of 3:1), reaction temperature of 60 ˚C for 1 h resulted in high catalysis over CB1 (89.57 %), followed by CB2 (87.46 %) and without catalyst (35.46 %). Large iodine number and high carbon content exhibited by CB1 was the probable reasoning for the accelerated activity of CB1 in the transesterification of WCO. To conclude, the present work showed a successful conversion of waste biomass into promising carbon catalyst for green synthesis of biodiesel from WCO.