Catalytic Oxidation Of Ethyl Acetate Research Articles

Metal-modified CeO2 nanobelts for catalytic oxidation of ethyl acetate: Roles of surface lattice oxygen and hydrolysis behaviors

Based on the comparison of three counterparts [Mg-, Al- and Cu-modified CeO2 nanobelts], it is illustrated that the low-temperature hydrolysis of ethyl acetate (EA) rapidly occurs and the removal of absorbed hydrolyzates (mainly acetates) is considered the rate-determining step. As the temperature increases, the escape of surface lattice oxygen (Os-latt) breaks through the shield of hydrolyzates and promotes the deep oxidation of intermediate products. Additionally, the activated Os-latt also facilitates the C-O bond cleavage in EA by nucleophilic attack. Due to the Os-latt escape, surface metal ions achieve more unsaturated coordinations to absorb the CH3COO– species, leading to competitive adsorption between O2 and hydrolyzates. The Cu modification strengthens the coordination adsorption of CH3COO– species, and the Al modification exhibits a low Os-latt mobility. These factors all contribute to a strong adsorption or accumulation of surface hydrolyzates. Therefore, a favorable ester hydrolysis-oxidation process over CeO2-based catalysts depends not only on excellent Os-latt mobility but also the suitable adsorption capacity of hydrolyzates, such as Mg modification.

Catalytic oxidation mechanism of ethyl acetate on O-ligand-single-atom-Ni/2-dimensional reduced graphene oxide: the essential role of the O ligand

The catalytic oxidation of ethyl acetate by SANi5-O-2DRGO is an example to display the electron transfer and detailed structural changes of the O ligand.

Catalytic oxidation of ethyl acetate over Y (Y = Cu, Mn, Co)-modified CeO2 derived from Ce-MOF

A series of YCe catalysts were prepared using Y-loaded (Y = Cu, Co, Mn) Ce-based metal–organic framework as a precursor. Mn-loaded CeO2 exhibited significantly better catalytic activity in the catalytic oxidation of ethyl acetate (EA) than noble metal catalyst. The relationship between the physicochemical properties of YCe catalysts and catalytic activity was studied by different characterization methods. The enhanced catalytic activity was attributed to the strong interaction between the transition metals and Ce, high specific surface area, abundant lattice defects, more oxygen vacacies and higher Olatt/(Olatt + Oads + Ow) molar ratios. The main intermediates in the oxidation of EA were ethanol, acetic acid, acetone, acetaldehyde and diethyl ether.

CuO/CeO2 catalysts prepared by modified impregnation method for ethyl acetate oxidation

The impregnation method is one of the most popular methods for preparing various types of supported catalysts. However, the preparation of highly active catalysts by the conventional impregnation method is still a great challenge. In this paper, a modified impregnation method (MI) was developed to prepare CuO/CeO2 catalysts for the catalytic oxidation of ethyl acetate (EA). It was found that the 5 %CuO/CeO2 catalyst (5-MI-500) prepared by MI method achieves 100% EA conversion at a low temperature of 200 °C. However, the temperature for 100% EA conversion over the 5 %CuO/CeO2 catalyst prepared by the conventional method is as high as 300 °C. Notably, the 5-MI-500 catalyst exhibits the highest proportion of well-dispersed CuO and Cu-O-Ce structures, which synergistically enhance catalyst activity. The well-dispersed CuO particles enhance the redox ability of the catalyst, while the Cu-O-Ce structure provides high activated oxygen via oxygen vacancy and better thermal stability during catalytic reaction. Accordingly, the possible reaction mechanism over the 5-MI-500 catalyst for EA oxidation was proposed. This study demonstrates that the MI method reported in this paper can provide a feasible methodology to prepare highly active catalysts with unique structures.

Effect of CuO species and oxygen vacancies over CuO/CeO2 catalysts on low-temperature oxidation of ethyl acetate

The catalytic oxidation of ethyl acetate (EA) was studied over CuO/CeO2 catalysts which were prepared by ball milling with different precursors (copper oxide, cerium acetate, cerium dioxide, copper acetate and cerium hydroxide). The CuO/CeO2 catalyst (O-A) prepared with copper oxide and cerium acetate as precursors shows very high catalytic activity that 100% EA conversion is achieved at low temperature of 220 °C. It is found that specific surface area (112.8 m2/g), particle size of CuO (3.5 nm) and proportion of oxygen vacancies are prominent on the O-A catalyst. Oxygen vacancies in CeO2 support are beneficial to enhancing the adsorption and activation of the oxygen. More finely dispersed CuO particles and oxygen vacancies which are derived from the synergistic interaction of Cu–Ce species play an important role in the catalytic oxidation of EA.

Birnessite MnO2 supported on CNTs in-situ for low-temperature oxidation of ethyl acetate

The removal of ethyl acetate has received much attention because excessive emissions of ethyl acetate are harmful to the environment and human health. Efficiently removing ethyl acetate under high space velocity requires low-cost catalysts operating at low temperatures. Herein, carbon nanotubes (CNTs) supported birnessite MnO2 catalysts were in-situ prepared by the redox reaction between KMnO4 and CNTs to maximize the interaction between MnO2 and support. The good thermal stability derived from the intact CNTs structure was important for the interaction between MnO2 and CNTs, contributing to the enhanced catalytic activity for ethyl acetate oxidation. 4MnO2-CNTs showed outstanding performance for the catalytic oxidation of ethyl acetate (100 ppm), achieving 100% removal efficiency and 99% CO2 selectivity at 160 °C under 100,000 mL·g−1·h−1 space velocity. In addition, 4MnO2-CNTs exhibited an excellent catalytic stability during the 50 h test period. Based on the comprehensive characterization study, we revealed that the activity of 4MnO2-CNTs could be effectively enhanced by the higher amount of active sites (Mn3+ and surface active adsorbed hydroxyl oxygen), as well as the strong interaction between MnO2 and support and the good thermal stability derived from the introduction of the intact CNTs structure.

Photothermal synergistic catalytic oxidation of ethyl acetate over MOFs-derived mesoporous N-TiO2 supported Pd catalysts

To overcome the main challenge of low photocatalytic efficiency and high energy consumption of thermocatalysis in the oxidation of volatile organic compounds (VOCs), MOF-derived mesoporous disk-like yPd/xN-TiO2 (x = 3.2, 5.5, 7.7 wt%, and y = 0.26 wt%) were prepared by ball milling-calcination method for photothermal catalytic oxidation of ethyl acetate. Morphological and pore structure characterization indicated that Pd/N-TiO2 had abundant pore structure and large specific surface area, which facilitated the adsorption of pollutants on the active sites. Among the catalysts, 0.26 Pd/3.2 N-TiO2 exhibited optimal photothermal catalytic performance. The corresponding temperature required for 50% and 90% conversion of ethyl acetate was 192 and 212 °C, with the specific reaction rate of 0.95 µmol/(gPd s) at 150 °C. Doping of N and loading of Pd nanoparticles enhanced the light absorption capacity, promoted the charge separation, and the adsorption capacity of ethyl acetate, resulting in a high photothermal catalytic oxidation activity. The detection of free radicals indicated that the photothermal synergy was associated with the generation of reactive oxygen species over 0.26 Pd/3.2 N-TiO2 under light irradiation condition, which directly participated in the catalytic removal of ethyl acetate. A proper increase in temperature could also promote the migration of carriers. The photothermal catalytic oxidation of VOCs over MOF-derivatives had great potential application for environmental protection.

Facile homogeneous precipitation method to prepare MnO2 with high performance in catalytic oxidation of ethyl acetate

Altering the urea decomposition rate in the homogeneous precipitation progress enabled the formation of various morphologies of α-MnO 2 . The decrease in crystalline size led to an increase in the surface area and dominance of the (2 1 1) crystal plane. The abundant surface oxygen species and high reducibility related to unsaturated manganese played critical roles in the decomposition of ethyl acetate. • A facile method driven by a synchronous reaction of urea hydrolysis and potassium permanganate reduction was proposed. • Pure α-MnO 2 with various morphologies was obtained by tuning reaction parameters. • Oxygen species on the (2 1 1) crystal plane were found to be most active in oxidation. • The optimal α-MnO 2 catalyst exhibited high and stable catalytic performance. A facile homogeneous precipitation method driven by synchronous reactions of urea hydrolysis and potassium permanganate reduction is proposed for preparation of MnO 2 catalysts. Pure α-MnO 2 nanostructures with different morphologies, including nanowires, nanorods and nanoparticles, were obtained by simply tuning the precipitation conditions. The evolution of materials derived from different preparation conditions was investigated via X-ray diffraction, transmission electron microscopy, N 2 adsorption, X-ray photoelectron spectroscopy, chemisorption and DFT calculations. The precipitation temperature and time significantly influenced the physiochemical properties of as-prepared catalysts. With increasing precipitation temperature and time, the degree of crystallinity, BET surface area and amount of surface-adsorbed oxygen of α-MnO 2 exhibited a substantial increase. The main exposed surface facets varied from (2 0 0), (3 1 0) to (2 1 1) as temperature and time increased. The best precipitation temperature and time were 90 °C and 24 h respectively. The optimal α-MnO 2 catalyst demonstrated 100% conversion of 1000 ppm ethyl acetate under the high space velocity of 78,000 h −1 during a 113-h test at 190 °C, outperforming other manganese oxide catalysts and many typical noble metal catalysts in terms of activity and stability. Experimental results and DFT calculations were consistent and indicated that surface oxygen species originating from the (2 1 1) surface of α-MnO 2 were most active. This study provides important insights for manipulating the morphology of MnO 2 by a facile method and remarkably promoting the performance for ethyl acetate VOC elimination.

Catalytic oxidation of ethyl acetate over CuO/ZSM-5 zeolite membrane coated on stainless steel fibers by chemical vapor deposition

CuO/ZSM-5/PSSF was synthesized by a combined wet lay-up papermaking, secondary growth and chemical vapor deposition (CVD) method for the catalytic oxidation of ethyl acetate in the fixed bed reactor. Ethanol and acetaldehyde are found during the oxidation and 3 wt% CuO/ZSM-5/PSSF catalyst exhibited the best performance with 90% conversion of 1500 ppm ethyl acetate at 254 °C with GHSV of 15,000 h−1, and the CuO/ZSM-5/PSSF exhibits low byproducts selectivity compared to granular CuO/ZSM-5 catalyst. Furthermore, the 3 wt% CuO/ZSM-5/PSSF catalyst exhibits a high stability after being used at 262 °C for 48 h.

Catalytic oxidation of ethyl acetate on Ce–Mn–O catalysts modified by La

La/Ce0.5Mn0.5 catalysts prepared by wetness impregnation of Ce0.5Mn0.5 with La(NO3)3 (aq) were used in catalytic oxidation of ethyl acetate. Characterization by X-ray diffractometer (XRD), H2 temperature programmed reduction (H2-TPR), X-ray photoelectron spectroscopy (XPS) and Raman shows that La/Ce0.5Mn0.5 catalysts have fluorite-like structure. La/Ce0.5Mn0.5 catalyst presents high activity with T90 (the temperature needed for 90% conversion) of 200 °C, where ethyl acetate is almost completely converted into CO2. The conversion at 195 °C maintains at 80% for at least 100 h. The intermediates were mainly ethanol and acetaldehyde whose amounts are below 250 × 10–6 and 16 × 10–6, respectively. In situ FTIR indicates that the modes of dissociative adsorption of ethyl acetate are related to surface oxygen species, which affect the stability of catalysts and the selectivity for ethanol and acetaldehyde intermediates.

The construction of three-dimensionally ordered macroporous (Fe, Zn, Cu, Co)/LaMnO3 with controllable gelation rate and their catalytic combustion properties

The gelation rate of LaMnO3 colloid was successfully modulated by introducing trace of tartaric acid and nitric acid simultaneously to construct 3DOM LaMnO3. To enhance surface oxygen vacancies, Fe, Zn, Cu and Co metal oxides were introduced on the surface of 3DOM LaMnO3 to modulate their surface composition, respectively. The morphology, crystalline, composition and reducibility of the prepared catalysts were characterized by SEM, XRD, XPS and TPR, respectively. The results showed that the surface oxygen defects can be enhanced distinctly with the introduction of metal oxides. Among the four metal oxides modified LaMnO3, the Co/LaMnO3 sample exhibited highest oxygen defects content and lowest reduction temperature. The catalytic properties of the five samples follow as the order: LaMnO3 < Fe/LaMnO3 < Zn/LaMnO3 ≈ Cu/LaMnO3 < Co/LaMnO3, which is consisted with that of their surface oxygen vacancies content, indicating that oxygen vacancies content is a crucial factor on catalytic oxidation of ethyl acetate.

Catalytic oxidation of ethyl acetate over silver catalysts supported on CeO2 with different morphologies

Abstract In this study, the Ag/CeO2 catalysts with three different morphologies of ceria nanocubes (CeO2-c), nanorods (CeO2-r) and nano-octahedra (CeO2-o) as supports were prepared by wet impregnation. Various characterizations such as XRD, BET, TEM/HRTEM, HAADF-STEM, XPS and H2-TPR were conducted, and a four step catalytic transformation was accordingly proposed. It was found that Ag/CeO2-c showed much more metallic Ag, active oxygen species and higher reducibility than those of Ag/CeO2-r and Ag/CeO2-o mainly due to the morphology effect. Ag/CeO2 and CeO2 catalysts were evaluated in the oxidation of ethyl acetate, and their catalytic activities were in the sequence of Ag/CeO2-c > Ag/CeO2-r > CeO2-r > CeO2-c > Ag/CeO2-o > CeO2-o. Besides, in-situ FTIR results revealed that the organic species on the catalyst surface were mainly acetates and adsorbed ethyl acetate for Ag/CeO2-c and CeO2-c, respectively, suggesting that addition of Ag promoted the complete oxidation of ethyl acetate.

Catalytic oxidation of ethyl acetate over Ru–Cu bimetallic catalysts: Further insights into reaction mechanism via in situ FTIR and DFT studies

In this work, ruthenium-based bimetallic catalysts of 1Ru-5 M/TiO2 (M = Co, Ce, Fe, Mn, Cu, Ni) were prepared and evaluated in ethyl acetate oxidation. It was found that 1Ru-5Cu/TiO2 gave the highest catalytic activity. The influence of CuO content and the preparation method on the catalytic activity was also studied. 1Ru-5Cu/TiO2 showed great catalytic stability in the on-stream reaction test. The influence of H2O on the catalytic activity is presented. The bimetallic catalyst 1Ru-5Cu/TiO2 showed better catalytic performance than the monometallic catalysts 1Ru/TiO2 and 5Cu/TiO2. XRD, TEM, HAADF-STEM, H2-TPR, and XPS characterizations were conducted, and the synergistic effect between Ru and Cu was well presented. In situ FTIR studies were also conducted, and the reaction intermediates were revealed on the catalyst surface. The theoretical calculations suggested that ethyl acetate is more easily adsorbed on the CuO surface, while it reacts more easily on the RuO2 surface. Accordingly, a reaction mechanism for the catalytic oxidation of ethyl acetate over a Ru-Cu bimetallic catalyst is proposed.

Catalytic oxidation of ethyl acetate over CuO/ZSM-5 catalysts: Effect of preparation method

Abstract A series of CuO/ZSM-5 catalysts with different copper loadings were prepared by impregnation (IM) and chemical vapor deposition (CVD) methods, respectively. Their physicochemical properties were investigated by N2 adsorption/desorption, X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectronic spectra (XPS), temperature-programmed reduction by hydrogen (H2-TPR) and temperature-programmed desorption of NH3 (NH3-TPD). The XRD and TEM results demonstrated that the crystallite size of the CuO prepared by CVD method was smaller than that by IM, and the XPS results illustrated that the copper specie was mostly in Cu2+ state and Cu+ co-existed. The performance of catalytic oxidation of ethyl acetate was conducted in the fixed-bed reactor based on CuO/ZSM-5 catalysts. The experimental results showed that the preparation method affected the catalytic activity of CuO/ZSM-5; the CVD catalysts exhibited a higher catalytic activity for ethyl acetate oxidation compared with the IM catalysts at the same copper loadings. Ethanol and acetaldehyde are observed to be the intermediate products in the combustion of ethyl acetate over the synthesized catalysts. The relative amounts of acetaldehyde and ethanol are determined by the selectivity of the catalyst toward acetaldehyde production from ethanol. Particularly, the 3 wt% CVD catalyst showed the best catalytic activity for ethyl acetate oxidation with 90% conversion of ethyl acetate at 235 °C, which was much lower than that of the 3 wt% IM catalyst (278 °C), meanwhile, the intermediate products of the 3 wt% CVD for ethyl acetate oxidation were completely oxidized into CO2 and H2O at temperature as low as 288 °C.

Catalytic oxidation of ethyl acetate over LaBO3 (B = Co, Mn, Ni, Fe) perovskites supported silver catalysts.

A series of silver catalysts supported on lanthanum based perovskites LaBO3 (B = Co, Mn, Ni, Fe) were synthesized and evaluated in the catalytic oxidation of ethyl acetate. XRD, BET, TEM/HRTEM, HAADF-STEM, XPS and H2-TPR were conducted, and the results indicate that redox activity of the catalysts is of great importance to the oxidation reaction. Activity tests demonstrated that Ag/LaCoO3 was more active than the other samples in ethyl acetate oxidation. Moreover, the CO2 selectivity, COx yields and byproduct distributions for all catalysts were studied, and Ag/LaCoO3 showed the best catalytic performance. Besides, Ag/LaCoO3 also showed excellent catalytic activity for other OVOCs.

Catalytic oxidation of ethyl acetate and toluene over Cu–Ce–Zr supported ZSM-5/TiO2 catalysts

Schematic of VOCs oxidation mechanism over the CCZ/Z (A) and CCZ/T (B) catalysts.

Catalytic oxidation of ethyl acetate over La-Co and La-Cu oxides

Lanthanum-containing mixed oxides (La-Co and La-Cu) were synthesized by several methods: exotemplating, evaporation, glycine-nitrate and glycine-nitrate-exotemplating. Samples were characterized by thermogravimetry and differential scanning calorimetry, N2 adsorption, temperature programmed reduction, scanning electron microscopy and X-ray diffraction. The materials obtained were tested as catalysts for ethyl acetate oxidation, as a model volatile organic compound. La-Cu samples showed poor catalytic performance, but La-Co materials were much more active than the individual components. Catalytic activity seems to be mainly determined by the easiness of reduction of the catalysts, which is related to the availability of oxygen from the lattice. Catalysts containing Co or Cu in excess of La (on a molar base) were more active than the corresponding mixed oxides consisting of equal amounts of La and the transition metal. Samples prepared by the evaporation method were more active than those prepared by exotemplating, for the same molar ratio. Samples prepared by evaporation and glycine-nitrate methods calcined at 600°C had a better performance than the corresponding oxides calcined at 300°C. The most active sample found in this study was the La-Co mixed oxide prepared by the glycine nitrate method and calcined at 600°C, 100% conversion of ethyl acetate to H2O and CO2 being achieved at 230°C.

Catalytic oxidation of ethyl acetate on cerium-containing mixed oxides

Cerium-containing mixed oxides (Ce–Cu, Ce–Ni and Ce–Co) were synthesized by exotemplating and evaporation methods. A carbon xerogel was used as template in the exotemplating procedure. The evaporation method was based on thermal decomposition of oxalates. Samples were characterized by thermogravimetry and differential scanning calorimetry, N2 adsorption at −196°C, temperature programmed reduction, scanning electron microscopy and X-ray diffraction. The materials obtained were tested as catalysts for ethyl acetate oxidation, as a model volatile organic compound. In general, materials with larger surface areas were achieved by exotemplating. Apart from the Ce–Cu oxides, the samples with a molar ratio of 1:2 had larger surface areas than the corresponding 1:1 materials. Smaller crystallite sizes were obtained with calcinations at lower temperatures. Materials prepared by evaporation were more active than those prepared by exotemplating and the 1:1 ratio was more favourable than 1:2. Full conversion of ethyl acetate was achieved at much lower temperatures with the mixed metal oxides, in comparison to single oxides. The most active materials were Ce–Co and Ce–Cu oxides. Ce–Ni oxide samples were the least active. Catalytic activity seems to be related not only with surface area, but also with the amount of Ce contained in the samples, calcination temperature (which influenced the particle size) and the reducibility of the catalysts.

Research on the Catalytic Activity of MnyCezOx/TiO2 for Ethyl Acetate Oxidation

Manganese and cerium based catalysts with different Mn/Ce molar ratios prepared by impregnation method for ethyl acetate oxidation. The activity tests of the samples were performed in a fixed-bed reactor. The effect of gas hourly space velocity (GHSV) and ethyl acetate concentration on the catalytic activity of the catalyst were also investigated. The results showed that these catalysts had high activity for the catalytic oxidation of ethyl acetate, of which the catalyst Mn0.9Ce0.1Ox/TiO2exhibitedthe bestactivity, and the temperature required for 90% conversion of ethyl acetate was at 216 °C. The catalyst Mn0.9Ce0.1Ox/TiO2still maintained high activity in the range of GHSV (16,500 to 48,500 h-1) and ethyl acetate concentration (4526 to 7092 mg/m3). In additional, experiments for measuring stability of Mn0.9Ce0.1Ox/TiO2were carried out, and experimental results showed that the good stability of Mn0.9Ce0.1Ox/TiO2was kept after it has run for 25 hours.

Exotemplated copper, cobalt, iron, lanthanum and nickel oxides for catalytic oxidation of ethyl acetate

Oxides of cobalt, copper, iron, lanthanum and nickel were prepared by an exotemplating method using two carbon materials as templates: carbon xerogel (CX) and a commercial activated carbon (AC). Samples were characterized by thermogravimetry and differential scanning calorimetry, N2 adsorption at −196°C, temperature programmed reduction, scanning electron microscopy and X-ray diffraction. All exotemplated samples showed improvements in surface area, compared with analogue commercial samples. The materials obtained were tested for ethyl acetate oxidation. CX was found to be a better templating material than AC, producing more active oxide materials. CX exotemplated NiO and Fe2O3 showed a large improvement in performance for the catalytic oxidation of ethyl acetate, compared to the commercial samples and AC analogues; nevertheless, CX exotemplated Co3O4 was the best catalyst. The commercial Co3O4 material showed also a good catalytic performance, being the most active of the commercial samples. However, some deactivation was observed with time. On the other hand, deactivation did not occur with the exotemplated material, which showed no decrease in performance up to 5 cycles and up to 72h of continuous operation (the maximum studied). The enhanced reducibility of exotemplated samples explains their better catalytic activities relatively to the commercial oxides.