CuO-In2O3 Catalysts Supported on Halloysite Nanotubes for CO2 Hydrogenation to Dimethyl Ether

Hydrogenation of CO2 relative to valuable chemical compounds such as methanol or dimethyl ether (DME) is an attractive route for reducing CO2 emissions in the atmosphere. In the present work, the hydrogenation of CO2 into DME over CuO-In2O3, supported on halloysite nanotubes (HNT) was investigated in the temperature range 200–300 °C at 40 atm. HNT appears to be novel promising support for bifunctional catalysts due to its thermal stability and the presence of acidic sites on its surface. CuO-In2O3/HNT catalysts demonstrate higher CO2 conversion and DME selectivity compared to non-indium CuO/HNT catalysts. The catalysts were investigated by N2 adsorption, X-ray diffraction, hydrogen-temperature programmed reduction and transition electron microscopy. The acid sites were analyzed by temperature programmed desorption of ammonia. It was shown that CuO/HNT was unstable under reaction conditions in contrast to CuO-In2O3/HNT. The best CuO-In2O3/HNT catalyst provided CO2 conversion of 7.6% with 65% DME selectivity under P = 40 atm, T = 250 °C, gas hour space velocity 12,000 h−1 and H2:CO2 = 3:1.

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Selective catalytic reduction of NO by Co-Mn based nanocatalysts

International Journal of Chemical Reactor Engineering ◽

10.1515/ijcre-2020-0240 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Vahid Zabihi ◽

Mohammad Hasan Eikani ◽

Mehdi Ardjmand ◽

Seyed Mahdi Latifi ◽

Alireza Salehirad

Keyword(s):

Selective Catalytic Reduction ◽

Catalytic Reduction ◽

Energy Dispersive ◽

Diffraction Field ◽

X Ray Diffraction ◽

X Ray ◽

Analysis Techniques ◽

Acidic Sites ◽

Temperature Window ◽

Temperature Programmed

Abstract One of the most significant aspects in selective catalytic reduction (SCR) of nitrogen oxides (NOx) is developing suitable catalysts by which the process occurs in a favorable way. At the present work SCR reaction by ammonia (NH3-SCR) was conducted using Co-Mn spinel and its composite with Fe-Mn spinel, as nanocatalysts. The nanocatalysts were fabricated through liquid routes and then their physicochemical properties such as phase composition, degree of agglomeration, particle size distribution, specific surface area and also surface acidic sites have been investigated by X-ray diffraction, Field Emission Scanning Electron Microscope, Energy-dispersive X-ray spectroscopy, energy dispersive spectroscopy mapping, Brunauer–Emmett–Teller, temperature-programmed reduction (H2-TPR) and temperature-programmed desorption of ammonia (NH3-TPD) analysis techniques. The catalytic activity tests in a temperature window of 150–400 °C and gas hourly space velocities of 10,000, 18,000 and 30,000 h−1 revealed that almost in all studied conditions, CoMn2O4/FeMn2O4 nanocomposite exhibited better performance in SCR reaction than CoMn2O4 spinel.

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The Effect of Zinc Content on n-Pentane Isomerisation Over Zn–S2O82–/ZrO2–Al2O3 Catalyst

Progress in Reaction Kinetics and Mechanism ◽

10.3184/146867816x14696245116981 ◽

2017 ◽

Vol 42 (1) ◽

pp. 23-29

Author(s):

Hua Song ◽

Shengnan Li ◽

Hualin Song ◽

Feng Li ◽

Huapeng Cui

Keyword(s):

Zinc Content ◽

Space Velocity ◽

X Ray Diffraction ◽

Sulfate Ions ◽

X Ray ◽

Weight Hourly Space Velocity ◽

Mass Fractions ◽

Crystallite Sizes ◽

Temperature Programmed ◽

Al2o3 Catalyst

A number of Zn–S2O82–/ZrO2–Al2O3 (Zn( x)–SZA) catalysts with different Zn mass fractions were synthesised and characterised by using X-ray diffraction, the Brunauer–Emmett–Teller method, and H2 temperature-programmed reduction. The structure and isomerisation performance of Zn( x)–SZA catalysts were studied using n-pentane as a probe reaction. The results showed that a pure tetragonal ZrO2 phase was formed on Zn( x)–SZA, and the ZrO2 crystallite sizes of the tetragonal phase increased in the order: Zn(0.5)–SZA < Zn(1.0)–SZA < Zn(1.5)–SZA < Zn(2.0)–SZA < SZA. Zn can strengthen the interaction between persulfate ions and the support, promote the formation of stronger acidity, lead to a better dispersion of sulfate ions on the surface, and improve the redox performance of the catalysts. The Zn(1.0)–SZA catalyst exhibited the best catalytic activity for n-pentane isomerisation. At a temperature of 170 °C, a reaction pressure of 2.0 MPa, a molar H2/ n-pentane ratio of 4:1, and a weight hourly space velocity of 1.0 h−1, the isopentane yield reached 58.0%.

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Mechanism and Performance of the SCR of NO with NH3 over Sulfated Sintered Ore Catalyst

Catalysts ◽

10.3390/catal9010090 ◽

2019 ◽

Vol 9 (1) ◽

pp. 90 ◽

Cited By ~ 10

Author(s):

Wangsheng Chen ◽

Fali Hu ◽

Linbo Qin ◽

Jun Han ◽

Bo Zhao ◽

...

Keyword(s):

Photoelectron Spectroscopy ◽

Catalytic Reduction ◽

Nox Reduction ◽

Space Velocity ◽

Acid Sites ◽

X Ray Diffraction ◽

X Ray ◽

Diffuse Reflectance Infrared Spectroscopy ◽

And Performance ◽

Diffuse Reflectance Infrared

A sulfated sintered ore catalyst (SSOC) was prepared to improve the denitration performance of the sintered ore catalyst (SOC). The catalysts were characterized by X-ray Fluorescence Spectrometry (XRF), Brunauer–Emmett–Teller (BET) analyzer, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and diffuse reflectance infrared spectroscopy (DRIFTS) to understand the NH3-selective catalytic reduction (SCR) reaction mechanism. Moreover, the denitration performance and stability of SSOC were also investigated. The experimental results indicated that there were more Brønsted acid sites at the surface of SSOC after the treatment by sulfuric acid, which lead to the enhancement of the adsorption capacity of NH3 and NO. Meanwhile, Lewis acid sites were also observed at the SSOC surface. The reaction between −NH2, NH 4 + and NO (E-R mechanism) and the reaction of the coordinated ammonia with the adsorbed NO2 (L-H mechanism) were attributed to NOx reduction. The maximum denitration efficiency over the SSOC, which was about 92%, occurred at 300 °C, with a 1.0 NH3/NO ratio, and 5000 h−1 gas hourly space velocity (GHSV).

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Nickel-Catalysed Vapour-Phase Hydrogenation of Furfural, Insights into Reactivity and Deactivation

Topics in Catalysis ◽

10.1007/s11244-020-01341-9 ◽

2020 ◽

Vol 63 (15-18) ◽

pp. 1446-1462 ◽

Cited By ~ 2

Author(s):

Kathryn L. MacIntosh ◽

Simon K. Beaumont

Keyword(s):

Furfuryl Alcohol ◽

Copper Chromite ◽

Catalyst Support ◽

Nickel Catalysts ◽

Vapour Phase ◽

X Ray Diffraction ◽

Temperature Programmed Oxidation ◽

Acidic Sites ◽

Supported Nickel Catalysts ◽

Temperature Programmed

AbstractFurfural is a key bioderived platform molecule, and its hydrogenation affords access to a number of important chemical intermediates that can act as “drop-in” replacements to those derived from crude oil or novel alternatives with desirable properties. Here, the vapour phase hydrogenation of furfural to furfuryl alcohol at 180 °C over standard impregnated nickel catalysts is reported and contrasted with the same reaction over copper chromite. Whilst the selectivity to furfuryl alcohol of the unmodified nickel catalysts is much lower than for copper chromite as expected, the activity of the nickel catalysts in the vapour phase is significantly higher, and the deactivation profile remarkably similar. In the case of the supported nickel catalysts, possible contribution to the deactivation by acidic sites on the catalyst support is discounted based on the similarity of deactivation kinetics on Ni/SiO2 with those seen for less acidic Ni/TiO2 and Ni/CeO2. Powder X-ray diffraction is used to exclude sintering as a primary deactivation pathway. Significant coking of the catalyst (~ 30 wt% over 16 h) is observed using temperature programmed oxidation. This, in combination with the solvent extraction analysis and infrared spectroscopy of the coked catalysts points to deactivation by polymeric condensation products of (reactant or) products and hydrocarbon like coke. These findings pave the way for targeted modification of nickel catalysts to use for this important biofeedstock-to-chemicals transformation.

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Temperature-programmed surface reactions of methanol and dimethyl ether on bifunctional catalysts for the direct synthesis of dimethyl ether from syngas

MATEC Web of Conferences ◽

10.1051/matecconf/201824300002 ◽

2018 ◽

Vol 243 ◽

pp. 00002

Author(s):

Olga Vodorezova ◽

Pavel Musich ◽

Natalia Karakchieva ◽

Lothar Heinrich ◽

Irina Kurzina

Keyword(s):

Dimethyl Ether ◽

Direct Synthesis ◽

Bifunctional Catalyst ◽

Bifunctional Catalysts ◽

X Ray Diffraction ◽

X Ray ◽

Physical Mixing ◽

Stage Synthesis ◽

Temperature Programmed ◽

Synthesis Of Dimethyl Ether

Dimethyl ether (DME) can be used as a replacement for diesel fuel in transportation. The catalytic effectiveness of bifunctional catalysts for DME one-stage synthesis from carbon monoxide and hydrogen was estimated in the paper. Bifunctional catalysts CuZnAl/HZSM-5, CuZnAlCr/HZSM-5, and CuZnAlZr/HZSM-5 were obtained by physical mixing of CuZnAl(Cr/Zr)– Ох and HZSM-5 components and were characterized by BET, X-ray diffraction, and temperatureprogrammed surface reaction methods. Based on the TPSR results, the mechanism of the interaction of methanol and DME with the surface of the bifunctional catalyst was studied. It was found that the temperature range of the greatest catalytic activity was 240–260 °С.

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The ZSM-5-Catalyzed Oxidation of Benzene to Phenol with N2O: Effect of Lewis Acid Sites

Catalysts ◽

10.3390/catal9010044 ◽

2019 ◽

Vol 9 (1) ◽

pp. 44

Author(s):

Cui Ouyang ◽

Yingxia Li ◽

Jianwei Li

Keyword(s):

Active Sites ◽

Acid Sites ◽

X Ray Diffraction ◽

Remarkable Feature ◽

Chemisorbed Oxygen ◽

Lewis Acidic Sites ◽

Acidic Sites ◽

Adsorption Desorption ◽

Oxidation Of Benzene ◽

N2o Selectivity

The oxidation of benzene to phenol (BTOP) with N2O as the oxidant has been studied with a variety of Fe/ZSM-5 catalysts. The literature has conclusively proven that Fe2+ sites are the active sites. However, some studies have suggested that the Lewis acidic sites (LAS) are responsible for the generation of the active chemisorbed oxygen. Nevertheless, there is no clear relationship between the LAS and the N2O selectivity to phenol. In an effort to elucidate the effects of LAS on BTOP with various ZSM-5 catalysts, we investigated the initial N2O selectivity to phenol. Here we show that the initial N2O selectivity to phenol is negative with the amount of LAS over a certain range. The catalyst H-ZSM-5-ST (H-ZSM-5 treated with water vapor) showed a remarkable initial N2O selectivity to phenol as high as 95.9% with a 0.021 mmol g−1 LAS concentration on the surface of the catalyst, while the Fe/ZSM-5 catalyst demonstrated the lowest initial N2O selectivity to phenol (11.7%) with the highest LAS concentration (0.137 mmol g−1). Another remarkable feature is that steaming was more effective than Fe ion exchange and high temperature calcining. The samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), N2-adsorption-desorption, UV-vis, NH3-TPD and pyridine Fourier transform infrared (FT-IR) techniques. Our results demonstrate how the concentration of LAS is likely to affect the initial N2O selectivity to phenol within a certain range (0.021–0.137 mmol g−1). This research has demonstrated the synergy between the active Fe2+ sites and LAS.

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Study on Preparation and Catalytic Properties of Pd/γ-Al2O3 Catalysts in One-Step Synthesis of Dimethyl Ether

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.66-68.1404 ◽

2011 ◽

Vol 66-68 ◽

pp. 1404-1409 ◽

Cited By ~ 4

Author(s):

Rui Zhi Chu ◽

Zhong Cai Zhang ◽

Ya Fei Liu ◽

Xian Liang Meng ◽

Zhi Min Zong ◽

...

Keyword(s):

Dimethyl Ether ◽

Catalytic Performance ◽

Acid Sites ◽

Co Conversion ◽

Dimethyl Ether Synthesis ◽

Acidic Sites ◽

One Step ◽

Space Time Yield ◽

Ether Synthesis ◽

Synthesis Of Dimethyl Ether

A series of Pd/γ-Al2O3 catalysts with different additons of Pd were prepared by impregnation. The effect of calcination condition and Pd loading on catalytic performance of catalysts for one-step dimethyl ether synthesis has been investigated. The physic-chemical performance and structure of Pd/γ-Al2O3 catalysts were characterized by CO-TPD, TGA and nitrogen physisorption. The results show that the dispersion of Pd and the amount of adsorbration on the CO-bridge of Pd could be increased to by the moderate microwave heating on the catalysts, and the catalyst performance can be improved. But a large number of surface acidic sites of Pd/γ-Al2O3 are covered by highly fragmented Pd-grain, it causes DME selectivity reduced. And the excessive Pd can reduce the samples’ surface acid, decrease the dispersion of the metal Pd and block up the pore of γ-Al2O3. The CO conversion rate and DME space-time yield could reach 60.1% and 28.76 mmol·g-1·h-1 respectively at 2% Pd loading, at this time Pd/γ-Al2O3 has a high Pd activity surface and ideal acid sites.

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CO2 Methanation of Biogas over 20 wt% Ni-Mg-Al Catalyst: on the Effect of N2, CH4, and O2 on CO2 Conversion Rate

Catalysts ◽

10.3390/catal10101201 ◽

2020 ◽

Vol 10 (10) ◽

pp. 1201

Author(s):

Danbee Han ◽

Yunji Kim ◽

Hyunseung Byun ◽

Wonjun Cho ◽

Youngsoon Baek

Keyword(s):

Reaction Temperature ◽

Photoelectron Spectroscopy ◽

Conversion Rate ◽

Space Velocity ◽

Molar Ratio ◽

Co2 Conversion ◽

X Ray Diffraction ◽

Co2 Methanation ◽

X Ray ◽

Ch4 Production

Biogas contains more than 40% CO2 that can be removed to produce high quality CH4. Recently, CH4 production from CO2 methanation has been reported in several studies. In this study, CO2 methanation of biogas was performed over a 20 wt% Ni-Mg-Al catalyst, and the effects of CO2 conversion rate and CH4 selectivity were investigated as a function of CH4, O2, H2O, and N2 compositions of the biogas. At a gas hourly space velocity (GHSV) of 30,000 h−1, the CO2 conversion rate was ~79.3% with a CH4 selectivity of 95%. In addition, the effects of the reaction temperature (200–450 °C), GHSV (21,000–50,000 h−1), and H2/CO2 molar ratio (3–5) on the CO2 conversion rate and CH4 selectivity over the 20 wt% Ni-Mg-Al catalyst were evaluated. The characteristics of the catalyst were analyzed using Brunauer–Emmett–Teller surface area analysis, X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy. The catalyst was stable for approximately 200 h at a GHSV of 30,000 h−1 and a reaction temperature of 350 °C. CO2 conversion and CH4 selectivity were maintained at 75% and 93%, respectively, and the catalyst was therefore concluded to exhibit stable activity.

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Self-Templating Synthesis of 3D Hierarchical NiCo2O4@NiO Nanocage from Hydrotalcites for Toluene Oxidation

Catalysts ◽

10.3390/catal9040352 ◽

2019 ◽

Vol 9 (4) ◽

pp. 352 ◽

Cited By ~ 10

Author(s):

Dongdong Wang ◽

Shuangde Li ◽

Yingchao Du ◽

Xiaofeng Wu ◽

Yunfa Chen

Keyword(s):

Photoelectron Spectroscopy ◽

Rational Design ◽

Space Velocity ◽

Acid Sites ◽

Step Method ◽

Zeolitic Imidazolate Framework ◽

Toluene Oxidation ◽

Synthetic Strategy ◽

Temperature Programmed ◽

High Space

Rational design LDHs (layered double hydroxides) with 3D hierarchical hollow structures have generated widespread interest for catalytic oxidation due to the high complexity in shell architecture and composition. Herein, we reported a handy two-step method to construct a 3D hierarchical NiCo2O4/NiO nanocage. This synthetic strategy contains a partial in situ transformation of ZIF-67 (zeolitic imidazolate framework-67) into Co-NiLDH yolk-shelled structures following ethanol etching, and a structure-preserved transformation from Co-NiLDH@ZIF-67 to a biphase nanocage following calcination. CoNi-yh-T (varied reaction time and calcination temperature) nanocages were investigated systematically by Brunauer–Emmett–Teller (BET), X-ray photoelectron spectroscopy (XPS), H2- temperature-programmed reduction (TPR), NH3-temperature-programmed desorption (TPD) and studied for toluene oxidation. The CoNi-6h-350 sample showed much higher activity with 90% toluene conversion (T90) at 229 °C at a high space velocity (SV = 60,000 mL g−1 h−1) than other catalysts (T90 >240 °C). Abundant surface high valence Co ions caused by the novel hierarchical nanostructures, together with adsorbed oxygen species and abundant medium-strength surface acid sites, played a key role for catalytic activities.

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Dry Reforming of Methane Using Ce-modified Ni Supported on 8%PO4 + ZrO2 Catalysts

Catalysts ◽

10.3390/catal10020242 ◽

2020 ◽

Vol 10 (2) ◽

pp. 242

Author(s):

Ahmed A. Ibrahim ◽

Ahmed S. Al-Fatesh ◽

Nadavala Siva Kumar ◽

Ahmed E. Abasaeed ◽

Samsudeen O. Kasim ◽

...

Keyword(s):

Space Velocity ◽

Catalyst System ◽

Dry Reforming ◽

Dry Reforming Of Methane ◽

Impregnation Method ◽

X Ray Diffraction ◽

Temperature Programmed Oxidation ◽

Active Metal ◽

Temperature Programmed ◽

The Stability

Dry reforming of methane (DRM) was studied in the light of Ni supported on 8%PO4 + ZrO2 catalysts. Cerium was used to modify the Ni active metal. Different percentage loadings of Ce (1%, 1.5%, 2%, 2.5%, 3%, and 5%) were tested. The wet incipient impregnation method was used for the preparation of all catalysts. The catalysts were activated at 700 °C for ½ h. The reactions were performed at 800 °C using a gas hourly space velocity of 28,000 mL (h·gcat)−1. X-ray diffraction (XRD), N2 physisorption, hydrogen temperature programmed reduction (H2-TPR), temperature programmed oxidation (TPO), temperature programmed desorption (TPD), and thermogravimetric analysis (TGA) were used for characterizing the catalysts. The TGA analysis depicted minor amounts of carbon deposition. The CO2-TPD results showed that Ce enhanced the basicity of the catalysts. The 3% Ce loading possessed the highest surface area, the largest pore volume, and the greatest pore diameter. All the promoted catalysts enhanced the conversions of CH4 and CO2. Among the promoted catalysts tested, the 10Ni + 3%Ce/8%PO4 + ZrO2 catalyst system operated at 1 bar and at 800 °C gave the highest conversions of CH4 (95%) and CO2 (96%). The stability profile of Cerium-modified catalysts (10%Ni/8%PO4 + ZrO2) depicted steady CH4 and CO2 conversions during the 7.5 h time on stream.

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