Conversion Of Acetic Acid Research Articles

Anaerobic Degradation of Aromatic and Aliphatic Biodegradable Plastics: Potential Mechanisms and Pathways.

Biodegradable plastics (BDPs) have been widely used as substitutes for traditional plastics, and their environmental fate is a subject of intense research interest. Compared with the aerobic degradation of BDPs, their biodegradability under anaerobic conditions in environmental engineering systems remains poorly understood. This study aimed to investigate the degradability of BDPs composed of poly(butylene adipate-co-terephthalate) (PBAT), poly(lactide acid) (PLA), and their blends, and explore the mechanism underlying their microbial degradation under conditions of anaerobic digestion (AD). The BDPs readily depolymerized under thermophilic conditions but were hydrolyzed at a slow rate under conditions of mesophilic AD. After 45 days of thermophilic AD, a decrease in the molecular weight and significant increase in the production of methane and carbon dioxide production were observed. Network and metagenomics analyses identified AD as reservoirs of plastic-degrading bacteria that produce multiple plastic-degrading enzymes. PETase was identified as the most abundant plastic-degrading enzyme. A potential pathway for the anaerobic biodegradation of BDPs was proposed herein. The polymers of high molecular weight were subjected to abiotic hydrolysis to form oligomers and monomers, enabling subsequent microbial hydrolysis and acetogenesis. Ultimately, complete degradation was achieved predominantly via the pathway involved in the conversion of acetic acid to methane. These findings provide novel insight into the mechanism underlying the anaerobic degradation of BDPs and the microbial resources crucial for the efficient degradation of BDPs.

Enhancement of hydrogen-rich gas production by acetic acid steam reforming: characterization of Ni–Co modified biochar-based catalysts

Abstract The development of cost-effective and highly efficient biochar-based catalysts is essential for the catalytic steam reforming process of bio-oil. In this study, pickling peanut shell biochar was used to prepare biochar-supported Ni/Co monometallic catalyst and biochar-supported nickel-Co bimetallic catalyst through the impregnation method. The catalytic effect of these catalysts on acetic acid (a bio-oil model compound) steam reforming was investigated. It was found that Co could enhance the dispersion of metal particles. The catalyst exhibited the best catalytic effect and significantly improved resistance to carbon deposition with a loading of 8 wt% and a Ni-to-Co ratio of 6:2. At the temperature of 600 °C and the S/C ratio of 3, the selectivity of H2 reached 84.48 %, and the conversion of acetic acid reached 95.49 %. A synergistic effect was observed between Ni and Co, leading to increased metal dispersion, enhanced reducibility, and a higher number of active centers. Co facilitates water dissociation and promotes the oxidation of C–H and mobile O, resulting in a faster decarbonization rate. The effective utilization of biochar-based catalysts and the rational utilization of bio-oil contribute to the timely achievement of carbon emission reduction targets.

Light-driven acetic acid coupling for the production of succinic acid

Treating and recycling high concentration acetic acid in the exhaust water has long posed a challenge in industry. These wastes containing acetic acid are typically processed via basic neutralization, characterized by high acidity and resistance to degradation, which can bring potential economic burden and environmental hazards. Here we report a new photocatalytic conversion route for addressing high concentrations of acetic acid. This process transforms acetic acid into valuable succinic acid through dehydrogenative coupling. Additionally, the photocatalytic conversion of acetic acid exhibits structure sensitivity when employing Pt cocatalysts of varying sizes. Through inhibiting the undesirable H termination of active free radicals over small Pt atoms and clusters, the rate of undesired decarboxylation reactions can be decreased by 75 %. This effectively enhances the selectivity of the coupling product succinic acid by 2.1 times, achieving a succinic acid formation rate of 7.28 mmol/(gcat•h). This work offers a theoretical guidance for searching value-added reaction pathways of acetic acid, thereby establishing an innovative approach for high concentration exhaust acetic acid treatment and converting low value monocarboxylic molecules into valuable diacid polymerization monomers under a mild and green condition.

Synthesis of Hydrocarbons over a Bifunctional Oxide/Zeolite catalyst – A Study on Intermediates

The direct conversion of syngas into hydrocarbons, catalyzed by a combination of metal oxide and acidic zeolite, has garnered increasing attention in the scientific community. The remarkable hydrocarbon selectivity achieved in the OX‐ZEO process is a key factor in this growing interest. This process involves two distinct steps: CO activation over the oxide and subsequent C‐C coupling within the zeolite pores, connected by an unidentified oxygenate intermediate. In this study, we explored three proposed oxygenates as potential intermediates and compared their conversion within the OX‐ZEO process. Using a bifunctional ZnCr2O4/H‐MOR catalyst in a syngas‐fed batch reactor, we found that methanol (MeOH) and dimethyl ether (DME) produced a hydrocarbon distribution similar to syngas conversion. However, the conversion of acetic acid (AcOH) resulted in a notably distinct range of hydrocarbons, including short olefins not detected with other reagents. Our findings suggest that methanol/DME might serve as active intermediates in the OX‐ZEO process over the ZnCr2O4/H‐MOR catalyst. This study provides a deeper insight into the transformation of proposed intermediates, contributing to the identification of the bridging intermediate that links the two catalytic functions.

Direct synthesis of acrylic acid from methanol and acetic acid over a constructed TiO2-coated NASICON catalyst

Direct conversion of methanol and acetic acid (HAc) into acrylic acid (AA) and methyl acrylate (MA) is remarkably significant for the high-value utilization of coal-based chemicals. However, the previous catalysts, due to their single function or poor synergy between multiple active sites, remain large challenges in direct synthesis of acrylic acid. Herein, we designed a novel catalyst system through coating TiO2 to sodium superionic conductor (NASICON) substrate for direct synthesis of acrylic acid from methanol and acetic acid. It was revealed that the catalyst with TiO2 coating showed obviously improved performance. The selectivity of AA+MA highly reached 56.1 % at 380 °C, corresponding to the spatiotemporal yield of 46.5 μmol·g−1·min−1. It was demonstrated that TiO2 coating catalyzes the oxidative dehydrogenation of methanol to formaldehyde, while NASICON substrate exerts important effects on the aldol condensation of formaldehyde and acetic acid, and their effective synergy promotes the direct synthesis of acrylic acid.

Sol-gel auto-combustion synthesis of bimetallic Pt-Co/Al2O3 catalysts for hydrogen production via acetic acid steam reforming

Green hydrogen production from renewable biomass via bio-oil catalytic steam reforming was a prospective technology. In order to accelerate the development of high-performance and long-term catalyst, we selected acetic acid as a typical bio-oil model compound to carry out the studies of steam reforming. Excellent bimetallic Pt-Co/Al2O3 catalysts were prepared using a sol-gel auto-combustion method. The effects of the molar ratio of ethylene glycol: citric acid: metal ions (EG/CA/M) on the catalyst structure and subsequent reforming performance were systematically investigated. It was found that the catalyst’s textural properties, reducibility, basic sites, and the dispersion of active metal could be carefully tuned by the EG/CA/M ratio. The catalyst prepared under EG/CA/M ratio of 6:3:1 performed the best reactivity in acetic acid steam reforming, showing a 97.6% acetic acid conversion and a 96.6% H2 yield at the reaction conditions of 650 °C, steam to carbon molar ratio of 5, and space velocity of 6957 h–1. Furthermore, a bifunctional reaction mechanism of acetic acid catalytic steam reforming was proposed by in-situ diffuse reflective infrared Fourier transform spectroscopy analysis coupled with density functional theory calculations.

Biogas upgrading towards acetic acid production using Clostridium thailandense supplemented with granular activated carbon (GAC) and L-arginine: A genomic analysis approach

This study explores the impact of granular activated carbon (GAC) and L-arginine supplementation on biogas upgrading and acetic acid production employing Clostridium thailandense. GAC and L-arginine concentrations ranged from 0 to 20 g/L and 0 to 5 g/L, respectively, with H2 acting as the electron donor at an H2 to CO2 ratio of 2:1 (v/v). Experiments were conducted at 30 °C with an agitation speed of 150 rpm. Additionally, gene annotation of the C. thailandense genome using Rapid Annotations using Subsystems Technology (RAST) identified genes involved in CO2 to acetic acid conversion. Results indicate that adding 7.5 g/L GAC boosts CH4 purity in biogas, elevating CO2 and H2 consumption efficiencies to 88.3 % and 98.7 %, respectively. This enhancement leads to a CH4 content increase to 93.3 %, accompanied by 0.90 g/L acetic acid production. Conversely, L-arginine demonstrates no significant impact on CO2 conversion. Leveraging RAST, the study identifies hydrogenase genes and NADH-dependent ferredoxin-NADP+ oxidoreductase (Nfn), as crucial for heightened H2 consumption efficiencies and cell growth facilitated by GAC, thus enhancing biogas upgrading efficiency in C. thailandense. This research provides vital insights into optimizing sustainable biogas production through strategic GAC utilization and elucidates the roles of hydrogenase genes and Nfn.

Potassium persulfate-glucose mediated synthesis of 3,3′-Bis(indolyl)methanes from arylacetic acid and indoles in water

An efficient and eco-friendly method has been developed for the preparation of 3,3′-bis(indolyl)methanes from indoles and aryl acetic acid is reported. The in-situ conversion of aryl acetic acid to their corresponding carbonyl compounds, and subsequent condensation with indoles was prompted by K2S2O8 in presence of glucose in water. The metal-free reaction with room temperature conditions, and wide substrate scope with good functional group tolerance are the salient features of the developed methodology.

Hydrophobic copper doped ceria-based catalyst for ketonization of acetic acid by suppressing water inhibition

Hydrophobizing the surface of catalysts is essential in many catalytic reactions confined by water, but it can be quite challenging for metal oxide catalysts because of their intricate structure and surface properties. Herein, a series of hydrophobic copper doped ceria-based catalysts was synthesized by introducing stearic acid over the surface of catalysts for the ketonization of acetic acid co-feeding with different concentration of water. Detailed investigations reveal that the stearic acid functionalization process obviously improves the hydrophobicity of Cu/CeO2 without greatly changing their structures. Due to the excellent hydrophobicity to inhibit water in the reaction system, ketonization activities of acetic acid were greatly improved over the hydrophobic Cu/CeO2 catalysts co-feeding with 10–65 mol.% water. Specifically, the acetic acid conversion and acetone yield reached 94 % and 87 % co-feeding with 47 % mol.% water at 330 °C over Cu/CeO2-2, respectively, outperforming stearic acid-free catalyst under the same conditions. Besides, the hydrophobic Cu/CeO2 catalyst was with good durability up to 10 h on stream. The promotion of catalytic activities gives more details to help future research into the design and development of catalysts for future industrial applications of ketonization.

Micro‐Mesoporous Hierarchical Beta Zeolite and its Catalytic Application in Acetic Acid Benzylation

AbstractHierarchical Beta zeolite with tailor‐made pore structure is prepared by post‐synthetic alkali (NaOH) treatment. XRD, FE‐SEM, ICP‐OES, 27Al & 29Si MAS NMR, and N2 sorption isotherms were used to explore the structural transformation of these materials. ICP‐OES analysis showed post‐synthetic base treatment resulting into tuning of the Si/Al ratio, thereby increasing the acidity of the sample. The acidic properties of materials were measured using acid‐base titration, Pyridine FTIR spectroscopy, and NH3‐TPD. Conversion of acetic acid to benzyl acetate by reacting with benzyl alcohol was studied using hierarchical and parent sample. The reaction was evaluated with theoretical and experimental approaches. Under optimum reaction conditions, desilicated Beta zeolite showed 93 % acetic acid conversion and 90 % benzyl acetate selectivity, as confirmed by GC and GC‐MS analyses. Theoretical analysis indicated direct relationship between rate constant and rising reaction temperature, in accordance with the principles of first‐order reaction kinetics (R2>0.95). The activation energy for acetic acid benzylation over Beta‐0.1 M NaOH was found to be 10.21 kJ mol−1, considerably lower value compared to previous reports.

Attapulgite-based MCM-41 zeolite supported Ni-Nb catalysts for hydrogen production by acetic acid steam reforming

Acetic acid steam reforming (AASR) was generally considered as one of the promising technologies for hydrogen production. In this work, the L-lysine-assisted attapulgite-based MCM-41 zeolite (LAMZ) was successfully synthesized by using attapulgite-derived silicon source and the LAMZ-supported Ni-Nb (xNi-yNb/LAMZ) catalysts were prepared via conventional impregnation method. The effects of LAMZ and Nb content on regulating the microstructures and properties of Ni-based catalysts were investigated by various characterizations. Results revealed that the addition of L-lysine could contribute to forming more void structures and increasing specific surface area of LAMZ support, which was beneficial for promoting the dispersion of active sites and enhancing the metal-support interaction. Additionally, Nb optimized the reduction of Ni, increased the concentration of surface-active Ni species, improved the strength of surface Lewis acid and promoted the formation of Ni-NbOx interfaces. Amongst, 5Ni-1Nb/LAMZ exhibited the highest surface Ni0 sites and Ni-NbOx interfaces, which further induces the generation of VO generation and the flow of lattice oxygen. Therefore, the 5Ni-1Nb/LAMZ catalyst presented the highest acetic acid conversion (82.1 %) and hydrogen yield (69.9 %) at reaction conditions of reaction temperature = 750 °C, S/C = 3, WHSV = 19.96 h−1, furthermore, it almost no any inactivation during 55 h of AASR. Additionally, the characterization results of spent catalysts confirmed that 5Ni-Nb/LAMZ possess high coke resistance and anti-sinter capability.

Green catalysis for the production of n-butyl acetate over phosphotungstic acid-encapsulated metal-organic framework UiO-67 catalyst: Catalyst preparation, characterization and reaction kinetics

In the present study, a composite of Keggin-type phosphotungstic acid encapsulated in sized-matched metal-organic framework UiO-67 (HPW@UiO-67) was successfully fabricated via a facile hydrothermal synthesis method and utilized for the preparation of n-butyl acetate. The as-synthesized composite catalyst was comprehensively characterized using FT-IR, PXRD, ICP-OES, N2 adsorption-desorption, SEM, TEM, NH3-TPD, TGA-DTG and XPS techniques. The characterization results confirmed that HPW was successfully immobilized in metal-organic framework without changing the structure of UiO-67. The asprepared HPW@UiO-67 catalyst exhibited higher esterification activity compared to the UiO-67 catalyst due to its suitable surface area and total volume, high dispersion of phosphotungstic acid and high total acidity. The kinetic study indicated that the process followed the second-order kinetic with the activation energy Ea = 53.1 kJ/mol. The catalyst exhibited good recovery and catalytic performance in the reuse study, maintaining the conversion of acetic acid above 63.1% after four reaction cycles. Moreover, the reaction mechanism for the synthesis of n-butyl acetate via esterification over HPW@UiO-67 was proposed.

Influence of Rh addition to transition metal-based catalysts in the oxidative steam reforming of acetic acid

In this work, the Rh-promotion to transition metal (Ni and Co) CeO2-supported catalysts has been studied for the first time on the acetic acid oxidative steam reforming. Characterization of the prepared catalysts confirmed the promoting effect of rhodium addition, allowing lower crystallite size which increases the number of available active sites to reactants, along with higher reducibility as evidenced by temperature-programmed reduction (H2-TPR). The influence of the reaction temperature on the acetic acid conversion and hydrogen yield was assessed. Co-based catalysts achieved better catalytic performance than Ni-based samples, almost complete acetic acid conversion, and hydrogen yields were close to the equilibrium values at temperatures over 500 ºC. On the other hand, tests at higher weight-hour space velocity evidenced the superior activity of Co-Rh/CeO2 sample. This sample showed good stability with almost complete acetic acid conversion after 25 h time-on-stream, decreasing only the hydrogen yield by 7% after the first 8 h along with a slight increase in the acetone yield of about 6%. This suggests that after the acetic acid ketonization, acetone steam reforming advanced to a lesser extent on the reaction mechanism because of long-term slight catalyst deactivation.

Co-solvent-assisted contra-diffusion assembly of COF membranes for intensifying esterification

Pervaporation is an effective technique to improve the conversion of acetic acid in the esterification reaction through in situ removing the product water. In this study, a co-solvent assisted contra-diffusion strategy was used to prepare covalent organic framework (COF) pervaporation membrane on the polyacrylonitrile porous substrate. Fatty alcohol was used as the co-solvent in the organic phase to tune the reaction region. Subsequently, the COFs were formed in the sub-surface of the substrate to form a nanoconfined composite membrane, which was then modified by polyvinyl alcohol through spinning coating. The obtained COF composite membranes were used to in situ remove water during the esterification from acetic acid and ethanol. Consequently, compared with the esterification without pervaporation, the conversion of acetic acid was enhanced from 74% to 90%, which exhibited an excellent intensification for the esterification reaction.

New Insights into the Conversion of Acetic Acid in Sodium Aluminate Solutions by AOPs

New Insights into the Conversion of Acetic Acid in Sodium Aluminate Solutions by AOPs

A novel approach to enhance methane production during anaerobic digestion of waste activated sludge by combined addition of trypsin, nano-zero-valent iron and activated carbon

A novel approach with a combination of trypsin, nano-zero-valent iron (NZVI) and activated carbon (AC) was conducted to promote the methane production of waste activated sludge (WAS) during the anaerobic digestion (AD) processes. Results showed that the combined addition of trypsin-NZVI-AC exhibited the synergistic effect during different AD stages. Trypsin mainly facilitated the hydrolysis process and the acetic acid conversion, while NZVI-AC enhanced the substrate metabolism and the electronic transfer to subsequently produce methane. A dose of 1000 mg/L trypsin was optimal to maximize this synergistic effect. Metagenomic analysis showed that trypsin-NZVI-AC addition effectively improved the relative abundance of acetyl-CoA carboxylase, and then strengthened both acetoclastic methanogenesis (M00357) and hydrogenotrophic methanogenesis (M00567). Hydrogenotrophic methanogens such as Methanobacterium, Methanoculleus, and Methanosarcina were greatly enriched with trypsin-NZVI-AC compared with trypsin or NZVI-AC addition. Moreover, electroactive bacteria G. sulfurreducens and G. metallireducens were also enriched by this method to conduct direct interspecies electron transfer among methanogens, leading to the better improvement of methane production. These findings supply a promising way to optimize the enzyme pretreatment technology and elevate the methanogenic efficiency of WAS.

Construction of catalytic pervaporation membrane with structure C/PAN/S to intensify esterification by in-site dehydration and proton providing

Catalytic pervaporation membrane can effectively promote the forward esterification reaction by in-site water removing and proton providing. A catalytic composite membrane (CCM) with structure C/PAN/S was proposed. To reduce the damage that the catalytic layer does to the separation layer, the intermediate support layer was designed between them. Two-dimensional material g-C3N4-SO3H was added to sodium alginate (SA) to improve the separation performance. The impregnation phase inversion method was applied to build a porous catalytic layer. Polyvinylpyrrolidone (PVP) was added as the porogen, which greatly reduced the mass transfer resistance. By introducing Amberlite 732, the membrane was endowed with an efficient and stable catalytic performance. The preparation conditions were investigated for better catalytic performance. Fourier transform infrared (FTIR) and scanning electron microscopy (SEM) were used in this work to characterize the materials and membranes. The flux of the catalytic composite membrane is 582 g·m−2·h−1, and the separation factor is 590. The acetic acid conversion rate reached 97.5%. The acetic acid conversion rate remained at 95.7% after five runs, showing outstanding stability. The separation factor of membranes with structure C/PAN/S increased 10 times. The developed catalytic composite membrane with structure C/PAN/S would have broad prospects in the catalytic membranes field.

Cd/SBA-15 heterogeneous catalyst used for acetic acid conversion: pseudo-homogeneous kinetic model, response surface methodology, and historical data design

Abstract Mesoporous materials (MMs) in the Santa Barbara Amorphous (SBA) family can be used as catalysts or support materials (SMs) for catalysts because they have controllable pore structure, thermal and chemical stability, and their surface properties can be modified easily depending on the desired reaction type. Surfactant (Pluronic p123; it is a symmetric triblock copolymer comprising poly and its chemical formula; HO(CH2CH2O)20(CH2CH(CH3)O)70(CH2CH2O)20H), a silica source (such as Tetraethyl orthosilicate: TEOS; SiC8H20O4), and a solvent are used in the synthesis of the SBA family (SBA-15). The SBA-15 was given with the hydrothermal method (HM) a catalyst feature by loading the active substance at a rate of 10, 25 % (cadmium/silica) by mass. Esterification reactions (ERs) were carried out with Cd-SBA-15 (Cd/Si: 10–25 %) catalyst at a feed rate of 1/2 (methanol/acetic acid), in the presence of 0.4 g catalyst, at a reaction temperature of 373 K and for 6–48 h. After 48 h, the catalytic activity (CA) values were obtained as 65 and 68 %, respectively. The re-usability of the catalysts was repeated two times under the same experimental conditions. It was observed that the catalysts maintained their catalytic activity of 73.35 and 68.72 % (3 × 48 h). In addition, the limited effect of catalyst amount on acetic acid conversion was investigated by Response Surface Methodology, and Historical Data Design. Moreover, k 1, k2, equilibrium constant and activation energy values were calculated using the pseudo-homogeneous kinetic model. The physical features of the catalysts were investigated by BET, XRD, FTIR, DRIFT, SEM/EDX, and MAPPING analysis methods.

A new ZrC nano powder solid acid catalyst for the esterification synthesis of ethyl acetate

Zirconium carbide nano powder was synthesized and used as a new ceramic solid acid catalyst for esterification reaction of acetic acid. The catalytic active atoms and centers and the types of associated orbitals in Lewis acid catalytic reaction were determined based on calculated electronic band structure and partial electronic density of state (PEDOS) of ZrC. The conversion percentage of acetic acid to ethyl acetate was measured by the by titration of residual acetic acid. The ZrC has a very good performance as a solid acid catalyst in the conversion of acetic acid to ethyl acetate.

Oxidative steam reforming of acetic acid on Ni catalysts: Influence of the La promotion on mesostructured supports

In this work, the support effect and the La2O3 promotion of Ni-based catalysts on the oxidative steam reforming of acetic acid as bio-oil model compound has been studied. Ni/SBA-15 showed the worst catalytic performance with an acetic acid conversion dropping below 30% at 500 °C ascribed to active phase oxidation. In contrast, Ni supported over mesoporous CeO2 (CeO2-m) reached better catalytic performance and lower coke formation due to the higher Ni dispersion and oxygen mobility of the support. On the other hand, La2O3 promotion to SBA-15 and CeO2-m led to even higher Ni dispersion and prevented sintering during the reforming reaction. This effect resulted in an improvement in the catalytic performance for both promoted samples. As a consequence of low Ni crystallite size and high oxygen mobility, Ni/La2O3–CeO2-m reached almost complete conversion (∼96%), the highest hydrogen yield (∼53%) maintained for 5 h with the lowest coke formation (62.3 mgcoke·gcat−1·h−1).