Environmental-Friendly Synthesis of Alkyl Carbamates from Urea and Alcohols with Silica Gel Supported Catalysts

TiO2/SiO2, Cr2O3-NiO/SiO2, and TiO2-Cr2O3/SiO2 were prepared by the impregnation method for alkyl carbamate synthesis using urea as the carbonyl source. Up to 97.5% methyl carbamate yield, 97% ethyl carbamate yield, and 96% butyl carbamate yield could be achieved, respectively. The catalysts were characterized by ICP-AES, BET, XRD, XPS, NH3-TPD, and EPMA. Catalytic activity investigation revealed that TiO2/SiO2, Cr2O3-NiO/SiO2, and TiO2-Cr2O3/SiO2 were effective catalysts for methyl carbamate (MC), ethyl carbamate (EC), and butyl carbamate (BC), respectively. The recycling tests suggested that these silica gel supported catalyst system is active, stable, and reusable. A total of 96–97% alkyl carbamate (methyl, ethyl, and butyl) could be obtained in a 2 L autoclave, and these data suggested that our catalyst system is relatively easy to scale up.

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CO Methanation as Alternative Refinement Process for CO Abatement in H2-Rich Gas for PEM Applications

International Journal of Chemical Reactor Engineering ◽

10.2202/1542-6580.1498 ◽

2007 ◽

Vol 5 (1) ◽

Cited By ~ 3

Author(s):

Camilla Galletti ◽

Stefania Specchia ◽

Guido Saracco ◽

Vito Specchia

Keyword(s):

Supported Catalysts ◽

Supported Catalyst ◽

Operating Conditions ◽

Impregnation Method ◽

Flow Meters ◽

Co Methanation ◽

Application Systems ◽

Selective Co Methanation ◽

Refinement Process ◽

O2 Supply

Theoretically, there are several methods that can be used to remove CO from H2-rich gases. As for the applications of PEM-FCs to vehicles, boats and yachts and residential co-generators, however, the feasible choice may be only between the preferential CO oxidation (CO-PROX) and the selective CO methanation (CO-SMET) because of the limited available spaces and low operating pressures in such application systems. The CO-PROX process has so far been extensively tested since it is somehow reliable to remove CO down to 10 ppmv by raising the O2 consumption unlimitedly. Nonetheless, the technology requires a closely controlled low O2 supply to keep the possibly lowest H2 parallel oxidation and a working temperature window suitably wide for control purposes. This, while making the method costly and complicated, obviously hampers its application to low-power PEM-FCs where very small oxidant flows have to be provided by use of well-refined expensive flow meters, such as mass flow meters. Without any additional reactant required, the CO-SMET can avoid the above-mentioned shortcomings of the CO-PROX application. Furthermore, the CO methanation is less exothermic than the CO and H2 oxidations. Thus, a CO-SMET reactor is inherently more easily controllable than a CO-PROX one. The present work deals with a screening of catalysts for CO abatement via selective methanation. Ru-based catalysts supported on TiO2, ZrO2 and CeO2 were prepared by a conventional impregnation method and CO removal was determined by varying the operating conditions. The obtained results showed good performances of the Ru/ZrO2 and Ru/CeO2 supported catalysts, and also the feasibility and applicability of the CO-SMET process, especially by employing the Ru/CeO2 supported catalyst.

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Development of Four Unit Processes for Biobased PLA Manufacturing

ISRN Polymer Science ◽

10.5402/2012/938261 ◽

2012 ◽

Vol 2012 ◽

pp. 1-6 ◽

Cited By ~ 4

Author(s):

Chae Hwan Hong ◽

Si Hwan Kim ◽

Ji-Yeon Seo ◽

Do Suck Han

Keyword(s):

Lactic Acid ◽

Ring Opening ◽

Lactic Acid Production ◽

Scale Up ◽

Catalyst System ◽

Ring Opening Polymerization ◽

Acid Fermentation ◽

Manufacturing Method ◽

Renewable Biomass ◽

Microbial Productivity

Polylactide (PLA), which is one of the most important biocompatible polyesters that are derived from annually renewable biomass such as corn and sugar beets, has attracted much attention for automotive parts application. The manufacturing method of PLA is the ring-opening polymerization of the dimeric cyclic ester of lactic acid, lactide. For the stereocomplex PLA, we developed the four unit processes, fermentation, separation, lactide conversion, and polymerization. Fermentation of sugars to D-lactic acid is little studied, and its microbial productivity is not well known. Therefore, we investigated D-lactic acid fermentation with a view to obtaining the strains capable of producing D-lactic acid, and we got a maximum lactic acid production 60 g/L. Lactide is prepared by a two-step process: first, the lactic acid is converted into oligo(lactic acid) by a polycondensation reaction; second, the oligo(lactic acid) is thermally depolymerized to form the cyclic lactide via an unzipping mechanism. Through catalyst screening test for polycondensation and depolymerization reactions, we got a new method which shortens the whole reaction time 50% the level of the conventional method. Poly(L-lactide) was obtained from the ring-opening polymerization of L-lactide. We investigated various catalysts and polymerization conditions. Finally, we got the best catalyst system and the scale-up technology.

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Efficient Oxidative Desulfurization (ODS) of Commercial Diesel with TBHP under Mild Conditions Catalyzed by Polymolybdates Supported on Al2O3

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1107.341 ◽

2015 ◽

Vol 1107 ◽

pp. 341-346

Author(s):

Wan Nazwanie Wan Abdullah ◽

Rusmidah Ali ◽

Wan Azelee Wan Abu Bakar

Keyword(s):

Sulfur Content ◽

Research Work ◽

Sulfur Removal ◽

Oxidative Desulfurization ◽

Catalyst System ◽

Impregnation Method ◽

Butyl Hydroperoxide ◽

Tert Butyl ◽

Alternative Method ◽

Tert Butyl Hydroperoxide

Due to the low specifications for sulfur content in diesel, a lot of research work are been conducted to develop alternative method for desulfurization. Catalytic oxidative desulfurization (Cat-ODS) has been found to be an alternative method to replace a conventional method which is hydrodesulfurization.New catalyst formulation using tert-butyl hydroperoxide polymolybdate based catalyst system was investigated in this research utilizing tert-butyl hydroperoxide (TBHP) as oxidant and dimethylformamide (DMF) as solvent for extraction. A series of polymolybdate supported alumina catalysts were prepared using wet impregnation method, ageing at ambient room temperature for 24 hours and followed by calcination process. A commercial diesel with 440 ppmw of total sulfur was employed to evaluate the elimination of sulfur compounds. Besides, the percentage of sulfur removal was measured by gas chromatography-flame photometric detector (GC-FPD). The sulfur content in commercial diesel was successfully reduced from 440 ppmw to 35 ppmw under mild condition followed by solvent extraction. From catalytic testing, Mo-Al2O3 calcined at 500°C was revealed as the most potential catalyst which gave 92% of sulfur removal.

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Butadiene polymerization over a π-allylnickel-alumina-silica gel catalyst system

Reaction Kinetics and Catalysis Letters ◽

10.1007/bf02065693 ◽

1980 ◽

Vol 13 (4) ◽

pp. 319-322 ◽

Cited By ~ 10

Author(s):

W. Skupiński ◽

M. Zawartke ◽

St. Malinowski

Keyword(s):

Silica Gel ◽

Catalyst System ◽

Butadiene Polymerization

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An Oxidation Study of Phthalimide-Derived Hydroxylactams

Molecules ◽

10.3390/molecules27020548 ◽

2022 ◽

Vol 27 (2) ◽

pp. 548

Author(s):

Bernard L. Adjei ◽

Frederick A. Luzzio

Keyword(s):

Silica Gel ◽

Systematic Study ◽

Special Interest ◽

Scale Up ◽

Reaction Times ◽

Pyridinium Chlorochromate ◽

Oxidation Study ◽

Full Conversion ◽

Oxidation System

A systematic study of the oxidation of 3-hydroxy-2-substituted isoindolin-1-ones (hydroxylactams) and their conversion to the corresponding phthalimides was undertaken using three oxidants. Of special interest was the introduction of nickel peroxide (NiO2) as an oxidation system for hydroxylactams and comparison of its performance with the commonly used pyridinium chlorochromate (PCC) and iodoxybenzoic acid (IBX) reagents. Using a range of hydroxylactams, optimal conversions of these substrates to the corresponding imides was achieved with 50 equivalents of freshly prepared NiO2 in refluxing toluene over 5–32 h reaction times. By comparison, oxidations of the same substrates using PCC/silica gel (three equivalents) and IBX (three equivalents) required oxidation times of 1–3 h for full conversion but required lengthier purification. While nominal amounts (~25 mg) of substrate hydroxylactams were used to ascertain conversion, scale-up procedures using all three methods gave good to excellent isolated yields of imides.

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Highly Active Catalysts Based on the Rh4(CO)12 Cluster Supported on Ce0.5Zr0.5 and Zr Oxides for Low-Temperature Methane Steam Reforming

Catalysts ◽

10.3390/catal9100800 ◽

2019 ◽

Vol 9 (10) ◽

pp. 800 ◽

Cited By ~ 1

Author(s):

Andrea Fasolini ◽

Silvia Ruggieri ◽

Cristina Femoni ◽

Francesco Basile

Keyword(s):

Low Temperature ◽

Steam Reforming ◽

Supported Catalysts ◽

Supported Catalyst ◽

Methane Steam Reforming ◽

Small Scale ◽

Methane Reforming ◽

Hydrogen Purification ◽

Highly Active ◽

Reforming Reactions

Syngas and Hydrogen productions from methane are industrially carried out at high temperatures (900 °C). Nevertheless, low-temperature steam reforming can be an alternative for small-scale plants. In these conditions, the process can also be coupled with systems that increase the overall efficiency such as hydrogen purification with membranes, microreactors or enhanced reforming with CO2 capture. However, at low temperature, in order to get conversion values close to the equilibrium ones, very active catalysts are needed. For this purpose, the Rh4(CO)12 cluster was synthetized and deposited over Ce0.5Zr0.5O2 and ZrO2 supports, prepared by microemulsion, and tested in low-temperature steam methane reforming reactions under different conditions. The catalysts were active at 750 °C at low Rh loadings (0.05%) and outperformed an analogous Rh-impregnated catalyst. At higher Rh concentrations (0.6%), the Rh cluster deposited on Ce0.5Zr0.5 oxide reached conversions close to the equilibrium values and good stability over long reaction time, demonstrating that active phases derived from Rh carbonyl clusters can be used to catalyze steam reforming reactions. Conversely, the same catalyst suffered from a fast deactivation at 500 °C, likely related to the oxidation of the Rh phase due to the oxygen-mobility properties of Ce. Indeed, at 500 °C the Rh-based ZrO2-supported catalyst was able to provide stable results with higher conversions. The effects of different pretreatments were also investigated: at 500 °C, the catalysts subjected to thermal treatment, both under N2 and H2, proved to be more active than those without the H2 treatment. In general, this work highlights the possibility of using Rh carbonyl-cluster-derived supported catalysts in methane reforming reactions and, at low temperature, it showed deactivation phenomena related to the presence of reducible supports.

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H2 Production from Catalytic Methane Decomposition Using Fe/x-ZrO2 and Fe-Ni/(x-ZrO2) (x = 0, La2O3, WO3) Catalysts

Catalysts ◽

10.3390/catal10070793 ◽

2020 ◽

Vol 10 (7) ◽

pp. 793

Author(s):

Fahad Al-Mubaddel ◽

Samsudeen Kasim ◽

Ahmed A. Ibrahim ◽

Abdulrhman S. Al-Awadi ◽

Anis H. Fakeeha ◽

...

Keyword(s):

Supported Catalysts ◽

Thermo Gravimetric Analysis ◽

Space Velocity ◽

H2 Production ◽

Methane Decomposition ◽

Gravimetric Analysis ◽

Impregnation Method ◽

Carbon Deposits ◽

Surface Areas ◽

H2 Yield

An environmentally-benign way of producing hydrogen is methane decomposition. This study focused on methane decomposition using Fe and Fe-Ni catalysts, which were dispersed over different supports by the wet-impregnation method. We observed the effect of modifying ZrO2 with La2O3 and WO3 in terms of H2 yield and carbon deposits. The modification led to a higher H2 yield in all cases and WO3-modified support gave the highest yield of about 90% and was stable throughout the reaction period. The reaction conditions were at 1 atm, 800 °C, and 4000 mL(hgcat)−1 space velocity. Adding Ni to Fe/x-ZrO2 gave a higher H2 yield and stability for ZrO2 and La2O3 + ZrO2-supported catalysts whose prior performances and stabilities were very poor. Catalyst samples were analyzed by characterization techniques like X-ray diffraction (XRD), nitrogen physisorption, temperature-programmed reduction (TPR), thermo-gravimetric analysis (TGA), and Raman spectroscopy. The phases of iron and the supports were identified using XRD while the BET revealed a significant decrease in the specific surface areas of fresh catalysts relative to supports. A progressive change in Fe’s oxidation state from Fe3+ to Fe0 was observed from the H2-TPR results. The carbon deposits on Fe/ZrO2 and Fe/La2O3 + ZrO2 are mainly amorphous, while Fe/WO3 + ZrO2 and Fe-Ni/x-ZrO2 are characterized by graphitic carbon.

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{CeO2/Bi2Mo1−xRuxO6} and {Au/Bi2Mo1−xRuxO6} Catalysts for Low-Temperature CO Oxidation

Catalysts ◽

10.3390/catal9110947 ◽

2019 ◽

Vol 9 (11) ◽

pp. 947 ◽

Cited By ~ 2

Author(s):

Edson Edain González ◽

Ricardo Rangel ◽

Javier Lara ◽

Pascual Bartolo-Pérez ◽

Juan José Alvarado-Gil ◽

...

Keyword(s):

Co Oxidation ◽

Photoelectron Spectroscopy ◽

Supported Catalysts ◽

Pollutant Emissions ◽

Impregnation Method ◽

Wet Impregnation ◽

X Ray ◽

Low Temperature Co Oxidation ◽

Carbon Dioxide Co2 ◽

Wet Impregnation Method

Nowadays, one of the most important challenges that humanity faces is to find alternative ways of reducing pollutant emissions. CeO2/Bi2Mo1−xRuxO6 and Au/Bi2Mo1−xRuxO6 catalysts were prepared to efficiently transform carbon monoxide (CO) to carbon dioxide (CO2) at low temperatures. The systems were prepared in a two-step process. First, Bi2Mo1−xRuxO6 supports were synthesized through the hydrothermal procedure under microwave heating. Then, CeO2 was deposited on Bi2Mo1−xRuxO6 using the wet impregnation method, while the incipient impregnation method was selected to deposit gold nanoparticles. The CeO2/Bi2Mo1−xRuxO6 and Au/Bi2Mo1−xRuxO6 catalysts were characterized using SEM microscopy and XRD. Furthermore, energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy were used. Tests were carried out for the supported catalysts in CO oxidation, and high conversion values, nearing 100%, was observed in a temperature range of 100 to 250 °C. The results showed that the best system was the Au/Bi2Mo0.95Ru0.05O6 catalyst, with CO oxidation starting at 50 °C and reaching 100% conversion at 186 °C.

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Catalytic Properties of Ni/CNTs and Ca-Promoted Ni/CNTs for Methanation Reaction of Carbon Dioxide

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.924.217 ◽

2014 ◽

Vol 924 ◽

pp. 217-226 ◽

Cited By ~ 5

Author(s):

Xiang Feng Hu ◽

Wen Yang ◽

Ning Wang ◽

Shi Zhong Luo ◽

Wei Chu

Keyword(s):

Carbon Dioxide ◽

Carbon Nanotubes ◽

Catalytic Activity ◽

Catalytic Properties ◽

Supported Catalyst ◽

Catalytic Performance ◽

Impregnation Method ◽

Methanation Reaction ◽

Ni Species ◽

Nickel Species

Nickel/carbon nanotubes (Ni/CNTs), Nickel/alumina (Ni/Al2O3), calcium-promoted Ni/CNTs and calcium-promoted Ni/Al2O3 were synthesized by impregnation method. Methanation of carbon dioxide was used as a probe to evaluate their catalytic performance. The features of these Ni-based catalysts were investigated via XRD, H2-TPR, H2-TPD and the N2 adsorptiondesorption isotherms. H2-TPR showed that nickel species on Ni/CNTs was reduced more easily with respect to that on Ni/Al2O3, and addition of Ca can increase the content of easily reducible Ni species for Ni/CNTs. XRD and H2-TPD indicated that addition of Ca promoted dispersion for CNTs-supported catalyst. These finding ultimately enhanced catalytic activity and stability for Ni/CNTs catalyst modified with Ca.

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Triphase Catalysis Using Silica Gel as Support

International Journal of Chemical Reactor Engineering ◽

10.1515/ijcre-2013-0007 ◽

2013 ◽

Vol 11 (1) ◽

pp. 347-352

Author(s):

T. Sankarshana ◽

J. Soujanya ◽

A. Anil Kumar

Keyword(s):

Potassium Permanganate ◽

Silica Gel ◽

Reaction Rate ◽

Phase Transfer ◽

Supported Catalysts ◽

Batch Reactor ◽

Kinetic Regime ◽

Rate Of Reaction ◽

Potential Applications ◽

Triphase Catalysis

Abstract The oxidation reaction of 2-ethyl-1-hexanol with potassium permanganate in the presence and absence of silica-gel-supported phase-transfer catalyst (PTC) in triphasic conditions was studied. In a batch reactor, the performance of the solid-supported catalysts was compared with unsupported catalyst and without the catalyst. The effect of speed of agitation, catalyst concentration, potassium permanganate concentration and temperature on reaction rate was studied. The reaction is found to be in the kinetic regime. The rate of reaction with the catalyst immobilised on the silica gel was less compared to the catalyst without immobilisation. Triphase catalysis with supported PTCs has potential applications in the continuous quest for greener industrial practices.

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