Co-precipitation Impregnation Methods Research Articles

Effect of Fe2O3 on ZrTiO4 support for NH3-SCR catalytic performance

The selective catalytic reduction (SCR) NH3 catalyst is mainly used in industrial production and automobile exhaust cleaning. In this study, a novel α%Fe2O3/ZrTiO4 (α=0, 8, 12, 15) catalyst was prepared by the coprecipitation impregnation method. The results show that the NOx conversion rate of 12%Fe2O3/ZrTiO4 catalyst with the optimal composition is high above 80% at 250−400 °C, close to 100% at 300 °C, and N2 selectivity is high above 90% at 200−450 °C. The redox properties, surface acidity, and Oβ/(Oα + Oβ) ratio of ZrTiO4 catalysts are improved after loading Fe2O3 on the ZrTiO4 surface, which is attributed not only to the porous structure of α%Fe2O3/ZrTiO4 catalyst but also to the synergistic interaction between the active component Fe2O3 and the support ZrTiO4. In addition, in-situ DRIFT reactions show that the NH3-SCR reaction of 12%Fe2O3/ZrTiO4 catalyst follows the Eley-Rideal mechanism. A clear reaction mechanism is conducive to a deeper understanding of the reaction process of NOx conversion during SCR. This work provides a feasible strategy for Fe-based SCR catalysts to replace V-based catalysts in the medium temperature range in the future.

Photocatalytic Degradation of Malachite Green by Layered Double Hydroxide Based Composites

Studies of LDH materials to be applied as photocatalyst for dye pollutant degradation have been developed. These interesting efforts are inseparable from the investigation of degradation performance and competitive synthetic methods. Composites based on Zn/Al and Mg/Al layered double hydroxides (LDHs) with ZnO and TiO2 were prepared by coprecipitation-impregnation method following by calcination at 300 °C to forms Zn/Al-ZnO, Mg/Al-ZnO, Zn/Al-TiO2, and Mg/Al-TiO2. Composites were characterized by XRD, FTIR, SEM and UV-DRS. Photodegradation of malachite green (MG) was carried out, after optimization of pH, catalyst loading and contact time in batch system under UV irradiation. XRD and spectroscopic data shows composites were successfully formed indicated by formation of both pristine materials. Degradation of malachite green showed that composites as photocatalyst have higher catalytic activity than pristine LDHs. LDH-ZnO composite have better activity, energy band gap and degradation reusability than LDH-TiO2. The Zn/Al-ZnO and Zn/Al-TiO2 composites degraded 97.1% and 96.3% MG, whereas the Mg/Al-ZnO and Mg/Al-TiO2 composites were able to degrade 99.8% and 98.6% MG, respectively. Copyright © 2022 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Enhancement of CO2 Reforming of CH4 Reaction Using Ni,Pd,Pt/Mg1−xCex4+O and Ni/Mg1−xCex4+O Catalysts

Catalysts Ni/Mg1−xCex4+O and Ni,Pd,Pt/Mg1−xCex4+O were developed using the co-precipitation–impregnation methods. Catalyst characterization took place using XRD, H2-TPR, XRF, XPS, Brunauer–Emmett–Teller (BET), TGA TEM, and FE-SEM. Testing the catalysts for the dry reforming of CH4 took place at temperatures of 700–900 °C. Findings from this study revealed a higher CH4 and CO2 conversion using the tri-metallic Ni,Pd,Pt/Mg1−xCex4+O catalyst in comparison with Ni monometallic systems in the whole temperature ranges. The catalyst Ni,Pd,Pt/Mg0.85Ce4+0.15O also reported an elevated activity level (CH4; 78%, and CO2; 90%) and an outstanding stability. Carbon deposition on spent catalysts was analyzed using TEM and Temperature programmed oxidation-mass spectroscopy (TPO-MS) following 200 h under an oxygen stream. The TEM and TPO-MS analysis results indicated a better anti-coking activity of the reduced catalyst along with a minimal concentration of platinum and palladium metals.

Preparation of highly selective and stable Cu–Mg–Fe catalyst and its catalytic performance for one-step synthesis of 2-ethylhexanol from n-butyraldehyde

A Cu–Mg–Fe catalyst was prepared by a coprecipitation–impregnation method and some influential factors such as Cu/Fe molar ratio, Mg/Fe molar ratio, calcination temperature and reduction temperature were investigated by means of XRD, XPS, NH3(or CO2)-TPD, H2-TPR and SEM analyses. Suitable preparation conditions were obtained as follows: a Cu/Mg/Fe ratio of 1:2:1, a calcination temperature of 550 °C, and a reduction temperature of 450 °C. The Cu–Mg–Fe catalyst showed a high catalytic performance for one-step synthesis of 2-ethylhexanol from n-butyraldehyde; the yield and selectivity of 2-ethylhexanol were 68.6% and 72.4% while the overall selectivity of C8 + C4 products was greatly improved to 96.9% under suitable reaction conditions.

Single-stage water gas shift reaction over structural modified Cu–Ce catalysts at medium temperatures: Synthesis and catalyst performance

Cu–Ce catalysts were synthesized by simple impregnation and coprecipitation-impregnation methods. The water gas shift reaction was investigated at medium temperatures. The impregnated 5Cu/CeO2 was regarded as optimum and resulted in 87% CO conversion, but showed 10% loss in activity over the 20h of time-on-stream. To increase stability, the coprecipitation-impregnation method was used and 5Cu/Ce10Cu recorded 89.2% CO conversion. Activity loss for all cases in this category was ≤2.7%. The activity and the stability results were validated by FESM, XRD, BET and H2-TPR analyses. The smallest crystalline size was found to produce the highest CO conversion. It was also found that catalyst stability strongly depended on Cu–Ce interaction and the cases with more stability had less BET change after the reaction. H2-TPR analysis showed that the Cu species were reduced to three phases (α, β and γ). It was determined that the interaction, activity and Cu–Ce stability relied on the surface area and β phase intensity. No methanation occurred in any case for either method.

Catalytic ozonation of diclofenac with iron silicate-loaded pumice in aqueous solution

The catalytic ozonation of diclofenac (DCF) with iron silicate-loaded pumice (FSO/PMC) in aqueous solution was investigated. FSO/PMC was synthesized by a co-precipitation–impregnation method and characterized using scanning electron microscope, N2 adsorption–desorption, X-ray fluorescence, and pHpzc measurements. Results showed that the FSO/PMC/O3 process obviously improved total organic carbon (TOC) removal efficiency from 32.3% (using sole ozonation) to 73.3% in 60 min. DCF mineralization in various oxidation processes was found to follow a two-stage pseudo-first-order kinetics. The presence of FSO/PMC effectively improved the mass transfer of ozone from gas to liquid phase and increased the efficiency of ozone decomposition, which results in the formation of •OH radicals. The ozonation of DCF generated large amounts of the ozone-refractory carboxylic acids, and these compounds were found to be continuously removed in the FSO/PMC/O3 process due to the catalytic activity of FSO/PMC. The synergetic effect between ozonation and FSO/PMC adsorption indicated that FSO/PMC is a promising catalyst for the ozonation process.

K-Promoted Co–CeO2 Catalyst for the Reverse Water–Gas Shift Reaction

Abstract A K-promoted Co–CeO2 catalyst prepared through the coprecipitation–impregnation method was shown to give a higher activity for the reverse water–gas shift reaction but with lower formation of the side product CH4. TPR results suggested that the addition of small amounts of K (1 wt %) improved the cobalt oxide reducibility through an electron-donation effect.

Study on Magnetic Mn<sub>0.2</sub>Co<sub>0.8</sub>Fe<sub>2</sub>O<sub>4</sub>/Silicalite-2 Catalyst and its Electro-Catalytic Property

Silicalite-2 zeolite was hydrothermally synthesized and Mn0.2Co0.8Fe2O4 magnetic nano-particle based on the Silicalite-2 zeolite carrier was prepared by a coprecipitation-impregnation method. The morphologies and microstructures of synthesized samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM). The heterogeneous catalytic oxidation electrolysis system of Mn0.2Co0.8Fe2O4/silicalite-2 was built by dispersing the catalysts in glass reactor for treating cationic brilliant red X-5GN wastewater. The SEM images showed that the structure of silicalite-2 zeolite remained its original after the introduction of Mn0.2Co0.8Fe2O4 magnetic particle. The XRD patterns revealed that Mn0.2Co0.8Fe2O4 oxides could not be observed on the surface of the silicalite-2 zeolite carrier. The experimental results showed that the dye wastewater with a satisfied decolorization rate (79.1%) was obtained when the initial pH was 6, the magnetic catalyst dosage was 0.4g/L, the electrolysis voltage was 2V, electrolytic time was 45min, respectively.

A CuZnAl-Based Hybrid Material for the Direct Synthesis of Dimethyl Ether from Syngas

A CuZnAl-based hybrid material was prepared by co-precipitation impregnation method using the active components of methanol synthesis material and pseudo-boehmite as the precursors. The as-prepared material was evaluated for the direct synthesis of dimethyl ether (DME) from syngas in a pressurized continuous flow fixed-bed reactor system. It was revealed that the hybrid material showed high activity and selectivity after an induced period, i.e. the CO conversion and DME selectivity reached as high as 81% and 67%, respectively. Moreover, it was observed that there was only slight carbon which could be eliminated rather than graphite carbon deposited on the material after run for 150 h, indicating its good stability for the direct synthesis process .

A CuZnAl-Based Hybrid Material for the Direct Synthesis of Dimethyl Ether from Syngas

A CuZnAl-based hybrid material was prepared by co-precipitation impregnation method using the active components of methanol synthesis material and pseudo-boehmite as the precursors. The as-prepared material was evaluated for the direct synthesis of dimethyl ether (DME) from syngas in a pressurized continuous flow fixed-bed reactor system. It was revealed that the hybrid material showed high activity and selectivity after an induced period, i.e. the CO conversion and DME selectivity reached as high as 81% and 67%, respectively. Moreover, it was observed that there was only slight carbon which could be eliminated rather than graphite carbon deposited on the material after run for 150 h, indicating its good stability for the direct synthesis process .

Effect of precipitants during the preparation of Cu-ZnO-Al 2O 3/Zr-ferrierite catalyst on the DME synthesis from syngas

The synthesis of dimethyl ether (DME) from biomass-derived model synthesis gas has been investigated on Cu-ZnO-Al 2O 3/Zr-ferrierite bifunctional catalysts. The catalysts are prepared by co-precipitation–impregnation method using Na 2CO 3, K 2CO 3 and (NH 4) 2CO 3 as the precipitants. The catalytic activity tests reveal that the best yield of DME can be obtained on the catalyst precipitated by using (NH 4) 2CO 3. Detailed characterization studies conducted on the catalysts to measure their properties such as surface area, acidity by temperature-programmed desorption of ammonia (NH 3-TPD), reducibility of Cu oxide by temperature-programmed reduction (TPR), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS) and copper surface area and particle size measurements by N 2O titration method. Increasing the number of moderate acidic sites and facilitation of easily reducible copper species with small particle size are found to be the prime reasons for the superior functionality of the (NH 4) 2CO 3 precipitated catalyst. The usage of (NH 4) 2CO 3 also leaves no residual ions, whereas the presence of residual K + and Na + ions in the case of K 2CO 3 and Na 2CO 3 precipitated catalysts leads to lower activity and selectivity.

Effect of aluminum on the morphological and textural properties of CuO–ZnO/H-Ferrierite

Hybrid catalysts containing CuO–ZnO or CuO–ZnO–Al 2O 3 as the metallic component and the zeolite H-ferrierite as support were prepared by both the coprecipitation–impregnation and coprecipitation–sedimentation methods. They were characterized by XRD, BET, and TEM. Aluminum was added to the metallic component, and the effects on the hybrid catalyst properties were studied. The metallic component blocked the zeolite micropore volume, and spaces were created between agglomerate particles of the first component, increasing mesopore volume. Aluminum introduction at a Cu/Zn/Al ratio of 55/30/15 favored the formation of hydrotalcite as a precursor to CuO/ZnO/Al 2O 3. In this case, small, highly dispersed particles of these oxides were obtained. In the coprecipitation–impregnation method, greater contact between the H-ferrierite zeolite and the metallic component was observed.

Partial oxidation of methane over Ni/Ce-Ti-O catalysts

Partial oxidation of methane (POM) was studied in this work. The supported nickel catalysts were prepared by the coprecipitation–impregnation method. The influence of the molar ratio of Ce/Ti, the calcination temperature, and the content of active component were investigated during the process of preparation. The results show that the mixed oxides of the Ce-Ti-O-supported Ni catalysts exhibited high catalytic activity and stability. Among the catalysts investigated, the highest catalytic activity was observed over 10 wt.% NiO/Ce0.50Ti0.50O2-700 °C which showed excellently stable performance during 100 h on stream at 750 °C. The catalysts were characterized by DTA/TG, BET, XRD, and TPR. XRD and TPR results confirmed that the NiO in all catalysts was highly dispersed. There was no NiO but only NiTiO3 in the NiO/TiO2 catalyst, due to the reaction between NiO and TiO2. NiTiO3 is harder to be reduced to Ni0 than NiO. The addition of CeO2 could form a solid solution of Ce-Ti-O, which was able to restrain the reaction between NiO and TiO2 and improve the storage capacity and mobility of oxygen. It was shown that Ni0 reduced from NiTiO3 was active for the POM reaction.

Effect of the Addition of Manganese and Zinc on the Properties of Copper-Based Catalyst for the Synthesis of Syngas to Dimethyl Ether

A series of copper-based catalysts supported on zeolite-Y were prepared through a coprecipitation impregnation method and used for the synthesis of dimethyl ether (DME) directly from synthesis gas (syngas) in a fixed-bed reactor. The conversion of CO and the selectivity of DME increased from 7.7% and 5.9% on Cu/zeolite-Y to 53.6 mol % and 63.5 mol % on Cu−Mn−Zn/zeolite-Y, respectively. The results of X-ray diffractometry (XRD), temperature-programmed reduction (TPR), and temperature-programmed desorption (TPD) showed that the reducibility, dispersion, and acid properties of Cu/zeolite-Y were strongly dependent on the addition of manganese and zinc, which affected the “synergistic effect” of the consecutive methanol synthesis from syngas and the steps for its dehydration to DME. The higher activity of Cu-Mn-Zn/zeolite-Y catalyst for DME synthesis was due to the good synergistic effect of the catalyst.

Design and elaboration of new solid acids for the synthesis of butylacetate

New and efficient solid-acid catalysts were designed and prepared by the coprecipitation-impregnation method, for the esterification of acetic acid and butanol synthesizing the butylacetate ester in fine chemical industry, in which the conventional catalyst was sulfuric acid. This work resulted in a cleaner process for acid-catalyzed reaction. The preparation parameters in the precipitation step and in the calcination were improved for a better performance. With the optimized new solid-acid catalyst, a good ester yield of 93.3% was achieved with the selectivity of 96.0%. The samples were characterized by XRD, N 2-adsorption and TGA measurements, the SO 4 2− anion was essential in the active structure.

Study of the Relationship Between Microstructure and Performance for No x Storage Catalysts

Aseries of Pt/BaAl2O4-Al2O3 NOx storage catalysts were prepared using the coprecipitation-impregnation method. XRD, XANES and EXAFS were used to characterize the microstructure of barium and platinum species in the samples. Barium exists in the forms of BaAl2O4 and BaCO3 crystallites. With the decreasing of calcination-temperature and barium content, the dispersion of BaAl2O4 phases becomes higher in the samples. In comparison with platinum standard compounds, the magnitude of the Pt-Pt coordination is significantly decreased, and the coordination distance is also shortened by about 0.01 nm. Platinum mainly exists as small atomic clusters, which possess a high dispersion, while some Pt (+ 4) species still present in the samples. A high dispersion of platinum and barium can greatly enhance the catalyst to store NOx.