Copper-based nanocatalysts for 2-butanol dehydrogenation: Screening and optimization of preparation parameters by response surface methodology

Elham Geravand,Zahra Shariatinia,Fereydoon Yaripour,Saeed Sahebdelfar 한국화학공학회 2015 Korean Journal of Chemical Engineering Vol.32 No.12

Two types of copper-based dehydrogenation nanocatalysts (Cu/ZnO/Al2O3 and Cu/SiO2) were prepared from various precursors by impregnation (IM), sol-gel (SG) and co precipitation (COPRE) methods. The structures of samples were characterized by N2 adsorption-desorption, XRD, XRF, TPR, N2O-Titration, FT-IR, FE-SEM and TEM techniques. The catalytic performance tests in vapor-phase dehydrogenation of 2-butanol to methyl ethyl ketone (MEK) were carried out in a fixed-bed reactor at a temperature of 260 oC under atmospheric pressure and LHSV of 4mL/(h·g cat). The experimental results indicated that (i) the copper oxide over the COPRE nanocatalyst was reduced at a lower temperature (222 oC) in comparison with the CuO reduced on the SG and IM samples (243 and 327 oC, respectively). Also, the percentage of reduction of CuO species on COPRE catalyst was the highest (98.8%) in comparison with the two other samples, (ii) the COPRE nanocatalyst exhibited the highest activity for the dehydrogenation of 2-butanol to MEK, and (iii) co-precipitation method was selected as an optimum method for preparation of nanocatalyst. The central composite experimental design method was applied for investigation of the effects of four critical preparation factors on the MEK selectivity of Cu/ZnO/Al2O3 nanocatalyst. The results showed that Cu/Zn molar ratio and precipitation pH are the most effective factors on the response and the optimum conditions for synthesis of Cu/ZnO/Al2O3 nanocatalyst with maximum selectivity of MEK were T(pre)=67.5 oC, T(aging)=68.8 oC, pH(pre)=7.27 and Cu/Zn molar ratio=1.38. The performance of the prepared nanocatalyst at the optimum conditions was comparable to the commercially available nanocatalyst.

Hydrophobicity in nanocatalysis

Alimoradlu, Khadijeh,Zamani, Asghar Techno-Press 2022 Advances in nano research Vol.12 No.1

Nanocatalysts are usually used in the synthesis of petrochemical products, fine chemicals, biofuel production, and automotive exhaust catalysis. Due to high activity and stability, recyclability, and cost-effectiveness, nanocatalysts are a key area in green chemistry. On the other hand, water as a common by-product or undesired element in a range of nanocatalyzed processes may be promoting the deactivation of catalytic systems. The advancement in the field of hydrophobicity in nanocatalysis could relatively solves these problems and improves the efficiency and recyclability of nanocatalysts. Some recent developments in the synthesis of novel nanocatalysts with tunable hydrophilic-hydrophobic character have been reviewed in this article and followed by highlighting their use in catalyzing several processes such as glycerolysis, Fenton, oxidation, reduction, ketalization, and hydrodesulfurization. Zeolites, carbon materials, modified silicas, surfactant-ligands, and polymers are the basic components in the controlling hydrophobicity of new nanocatalysts. Various characterization methods such as N2 adsorption-desorption, scanning and transmission electron microscopy, and contact angle measurement are critical in the understanding of hydrophobicity of materials. Also, in this review, it has been shown that how the hydrophobicity of nanocatalyst is affected by its structure, textural properties, and surface acidity, and discuss the important factors in designing catalysts with high efficiency and recyclability. It is useful for chemists and chemical engineers who are concerned with designing novel types of nanocatalysts with high activity and recyclability for environmentally friendly applications.

Viscosity reduction of extra-heavy crude oil using nanocatalysts

Seyed Amir Sabet,Mohammadreza Omidkhah,Arezou Jafari 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.5

Exploiting extra-heavy crude oil and converting it to operational products is considered a challenging processin the industry due to the difficulty in processing this kind of crude oil. So, in the present study, viscosity reductionof extra-heavy crude oil is inquired using nanocatalysts. This is the first study that investigates and juxtaposes theresults of viscosity reduction of extra-heavy crude oil based on direct heating and microwave radiation as the indirectheating source at the presence of ZSM-5 catalyst as well as silica, clay, and synthesized nickel oxide nanocatalysts inorder to facilitate the process of extra-heavy crude oil upgrading. The results illustrate that nanocatalysts have a fundamentalimpact on the viscosity reduction of extra-heavy crude oil. According to the findings, nanosilica represents thebest efficiency among others as it makes a 98.3% reduction in the extra-heavy crude oil viscosity. Besides, the applicationof microwave radiation in the upgrading of extra-heavy crude oil leads to an incredible reaction duration reduction asapproximately 60% of sample oil viscosity is reduced in just 90 seconds. Analysis of upgraded oil reveals that addingexcess nanocatalyst to the extra-heavy crude oil actuates an efficiency reduction due to the agglomeration of nanoparticles. Finally, the findings offer appealing information for the enhancement of upgrading processes in the industry.

Synthesis and physicochemical characterizations of Ni/Al2O3–ZrO2 nanocatalyst prepared via impregnation method and treated with non-thermal plasma for CO2 reforming of CH4

Nader Rahemi,Mohammad Haghighi,Ali Akbar Babaluo,Mahdi Fallah Jafari,Pooya Estifaee 한국공업화학회 2013 Journal of Industrial and Engineering Chemistry Vol.19 No.5

Ni/Al2O3 and Ni/Al2O3–ZrO2 nanocatalysts synthesized via impregnation and treated with non-thermal plasma were investigated in dry reforming of methane. The results showed that plasma treatment produces highly dispersed nanoparticles with a high surface area. Strong interaction between active phase and support particles in plasma-treated catalysts can be concluded based on XRD and XPS results. Smaller Ni particles with narrow particle size distribution were observed in plasma-treated Ni/Al2O3–ZrO2 nanocatalyst. The catalytic activity of plasma-treated Ni/Al2O3–ZrO2 was higher than that of conventional catalyst, resulting in operating conditions with considerably lower temperatures. Long reaction times confirmed the stability of the plasma-treated Ni/Al2O3–ZrO2 nanocatalyst.

Hydrogenolysis of nitrosodimethyl amine in gas phase over Au/γ-Al2O3 nanocatalyst

Shahram Ghanbari Pakdehi,Fariba Fazeli 한국화학공학회 2014 Korean Journal of Chemical Engineering Vol.31 No.7

Nitrosodimethyl amine (NDMA), as a carcinogenic byproduct in production of unsymmetrical dimethylhydrazine (UDMH) in space industries, should be decomposed in the vapor phase. A suitable method for this purpose isselective catalytic hydrogenolysis of NDMA over Au/γ-Al2O3 nanocatalyst. We synthesized and characterized the Au/γ-Al2O3 nanocatalyst by homogeneous deposition-precipitation (HDP)/DP-urea method. Activity of the catalyst was influencedby nanosized Au particles, Au loading and the bed temperature. The optimum parameters for the catalyst were:Au particles <5 nm, Au loading at 1.5 wt% and bed temperature of 35-45 oC. The reaction was strongly sensitive tothe Au particle size. The reaction occurred over the catalyst to produce dimethyl amine (DMA) and nitroxyl in a selectivemanner. The kinetics of NDMA hydrogenolysis over the nanocatalyst was studied in an integral fixed bed reactor. Thereexisted a consistency with the Langmuir-Hinshelwood mechanism involving dissociative adsorption of H2 and NDMA.

Cylindrical core-shell tween 80 micelle templated green synthesis of gold-silver hollow cubic nanostructures as efficient nanocatalysts

Joseph, Dickson,Lee, Hoomin,Huh, Yun Suk,Han, Young-Kyu Elsevier 2018 Materials & Design Vol.160 No.-

<P><B>Abstract</B></P> <P>The non-ionic surfactant, Tween 80 (T80) a material with promising applications in the pharmaceutical, cosmetic, and food industries, has been explored here for the design of novel nanostructures (NS). We report here a direct one-pot seedless green method for the synthesis of gold-silver (AuAg) hollow cubic NS, with gold (90%) being the major component. The concentration of T80 plays an important role in determining the shape of the NS. A minimum T80 concentration of 50 mM is required for the formation of hollow cubic NS, whose sizes are controlled by increasing the T80 concentration. The unique molecular structure of T80 directs its molecules to assemble into core-shell cylindrical micelles that act as a soft-template for the growth of the NS. Study of the mechanism for the formation of the NS suggests nucleation followed by co-reduction of metal ions and its growth into hollow cubic NS over T80 micelles. The AuAg hollow cubic NS shows greater potential as efficient nanocatalysts than the non-cubic NS obtained at lower T80 concentrations. The hollowness and the cubic shape of the NS contribute towards their effective surface area that facilitates efficient catalytic activity. The AuAg NS may have biological applications due to their cell viabilities.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A green, direct, one-pot, seedless route towards the synthesis of hollow cubic nanostructures has been successfully developed. </LI> <LI> The hollow cubic nanostructures are made up of a bimetallic gold-silver alloy, with gold as the major component. </LI> <LI> Tween 80, a non-ionic surfactant's core-shell cylindrical micellar structure guides the shape of the nanostructures. </LI> <LI> The prepared nanostructures are biocompatible and act as efficient nanocatalysts. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Tween 80, a biocompatible non-ionic surfactant as a soft-template for the synthesis of novel gold-silver hollow cubic nanostructures as nanocatalysts, using a direct one-pot seedless method in aqueous medium.</P> <P>[DISPLAY OMISSION]</P>

Mesoporous CexZr1−xO2 solid solutions supported CuO nanocatalysts for toluene total oxidation

Qing-Fang Deng,Tie-Zhen Ren,Bao Agula,Yuping Liu,Zhong-Yong Yuan 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.5

Mesoporous CexZr1 xO2 solid solutions were prepared by the surfactant-assisted method and used as support of CuO nanocatalysts for catalytic total oxidation of toluene. The prepared CuO/CexZr1 xO2 catalysts have a wormhole-like mesoporous structure with high surface area and uniform pore size distribution, and the CuO nanoparticles were highly dispersed on the surface of CexZr1 xO2. The doping of ZrO2 in CeO2 promotes the dispersion of active copper species and enhances the reducibility of copper species. The effect of Ce/Zr ratio, calcination temperature and CuO loading amount on the catalytic performance of CuO/CexZr1 xO2 was investigated in detail. The 400 ℃-calcined 8%CuO/Ce0.8Zr0.2O2 catalyst exhibits the highest activity with the complete toluene conversion temperature of 275 ℃ at the condition of GHSH = 33,000 h-1 and the toluene concentration of 4400 ppm. The interfacial interaction between CuO and the CexZr1 xO2 support, highly dispersed CuO nanoparticles and the nature of the support contribute to the high catalytic activity of mesoporous CuO/CexZr1 xO2 nanocatalysts.

Surface effect of platinum catalyst-decorated mesoporous carbon support using the dissolution of zinc oxide for methanol oxidation

An, Geon-Hyoung,Jo, Hyun-Gi,Ahn, Hyo-Jin Elsevier 2019 APPLIED SURFACE SCIENCE - Vol.473 No.-

<P><B>Abstract</B></P> <P>Due to their excellent chemical stability, as well as low operating temperature, high energy density, and environment-friendliness, carbon supports are a prospective candidate for platinum (Pt) nanocatalysts in direct methanol fuel cells (DMFCs). However, numerous efforts to achieve the high efficiency for the energy conversion by carbon supports have faced considerable challenges owing to an inefficient utilization of the inside region, leading to the low electrochemical performance. Thus, in the present study, we propose an advanced surface technology for the mesoporous structure. The obtained Pt nanocatalyst-decorated mesoporous carbon nanofiber support offers a high anodic current density of 732 mA mg<SUB>Pt</SUB> <SUP>−1</SUP>, and an excellent catalytic stability as compared to the commercial Pt/C (20 wt% Pt on Vulcan carbon, De Nora S.P.A.) and Pt/CNF. Due to these characteristics, this advanced carbon support provides several, benefits such as the well-dispersed Pt nanocatalysts on the surface, as well as achieves a superb catalytic stability. In sum, the advanced carbon support is a promising candidate to improve the electrochemical performance of DMFCs.</P> <P><B>Highlights</B></P> <P> <UL> <LI> High efficiency for the energy conversion by carbon supports. </LI> <LI> Inefficient utilization of the inside region for carbon supports. </LI> <LI> Well-dispersed Pt nanoparticles on supports. </LI> <LI> Improved electrochemical performance of methanol oxidation reaction. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Improved Kerosene Quality with the Use of a Gamma Alumina Nanoparticles Supported Zinc Oxide Catalyst in a Digital Batch Baffled Reactor: Experiments and Process Modelling

Jasim I. Humadi,Ghassan Hassan Abdul Razzaq,Luay Ahmed Khamees,Mustafa A. Ahmed,Liqaa I. Saeed 한국화학공학회 2023 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.61 No.2

To create an environmentally sustainable fuel with a low sulfur concentration, requires alternative sulfur removal methods. During the course of this study, a high surface gamma alumina-supported ZnO nanocatalyst with a ZnO/-Al2O3 ratio of 12% was developed and tested for its ability to improve the activity of the oxidative desulfurization (ODS) process for the desulfurization of kerosene fuel. Scanning electron microscopy (SEM) and Brunauer-Emmett- Teller (BET) were used to characterize the produced nanocatalyst. In a digital batch baffled reactor (20~80 min), the effectiveness of the synthesized nanocatalyst was tested at different initial concentrations of dibenzothiophene (DBT) of 300~600 ppm, oxidation temperatures (25~70 ℃), and oxidation periods (0.5, 1, and 2 hours). The baffles included in the digital baffled batch reactor resist the swirling of the reaction mixture, thus facilitating mixing. The ODS procedure yielded the maximum DBT conversion (95.5%) at 70 ℃ with an 80-minute reaction time and an initial DBT level of 600 ppm. The most precise values of kinetic variables were subsequently determined using a mathematical modelling procedure for the ODS procedure. The average absolute error of the simulation findings was less than 5%, demonstrating a good degree of agreement with the experimental results acquired from all runs. The optimization of the operating conditions revealed that 99.1% of the DBT can be removed in 140 minutes.

Catalytic hydrogenation of organic dyes by Ag nanoparticles on reduced graphene oxide

Bruno C. Mascarenhas,Laudemir C. Varanda 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.103 No.-

Stable, efficient, and reusable catalysts for wastewater treatment, promoting the catalytic elimination ofenvironmental pollutants remains a current challenge. This work shows a one-pot synthesize Agnanoparticles (AgNPs) supported on reduced graphene oxide (rGO/Ag) as a nanocatalyst. Morphological control of AgNPs was achieved by adding NH4OH during the nucleation and growth processesleading to the spherical nanoparticles with average size of 9 ± 3 nm). Temperature increase promotesdecrease of the oxygenated functional groups on rGO sheets, with an ID/IG = 0.57 at 300 C. Catalyticactivity of rGO/Ag was investigated through the catalytic hydrogenation of methylene blue (MB) and rhodamineB (RhB) in the presence of NaBH4 as a reducing agent. The proposed mechanism is based on thetransfer of 2e and 1H+ between the nanocatalyst and the dye molecules. Dyes adsorption on the catalystis a rate-determining step and was accelerated by the rGO support. X-ray photoelectron spectroscopyanalysis before and after successive catalytic cycles indicated that the catalyst integrity was maintained,with a slight decrease in the silver amount from 4.53 to 3.78 at%. The decolorization reaction followed thepseudo-first-order kinetics model for both dyes, and our results showed an efficiency of around 30%higher than similar methods.