CO2Oxidative Dehydrogenation of Ethane to Ethylene over Cr/MCM-41 Nanocatalyst Synthesized via Hydrothermal/Impregnation Methods: Influence of Chromium Content on Catalytic Properties and Performance

Asghari, Elmira; Haghighi, Mohammad; Rahmani, Farhad

doi:10.1016/j.molcata.2016.03.033

Cited by 68 publications

(46 citation statements)

References 38 publications

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“…The isolated Cr can be located on the support, interface, steps and edges, et.al. On the other hand, the high amount of OH groups allows us to expect a better stability of the catalyst by suppressing the coke deposition during the reaction ,. Thus, a decrease in the activity for PDH process over the 15Cr/MCM‐41 catalyst with low intensity of OH groups is obtained.…”

Section: Resultsmentioning

confidence: 99%

Investigation of the Isolated Cr(VI) Species in Cr/MCM‐41 Catalysts and its Effect on Catalytic Activity for Dehydrogenation of Propane

Zhang

Yang

et al. 2018

ChemCatChem

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Cr‐modified MCM‐41 with different loadings were prepared and tested in the propane dehydrogenation (PDH) reaction. As for Cr/MCM‐41 system, the general knowledge was that high Cr loadings resulted in the reduction of silica surface hydroxyl groups, thus leading to the formation of inactive Cr(III) species, as clusters and/or crystalline Cr2O3. However, in the present work, isolated Cr(VI) states were identified in the Cr/MCM‐41 catalysts, instead of Cr(III) species, using UV‐vis and H2‐TPR. These isolated Cr(VI) species are difficult to reduce, causing the decreased activity for propane conversion and low selectivity towards C3H6 in the PDH process. In contrast, a good dispersion of the Cr species was obtained using a chromium column adsorption process, and the absence of the isolated state of Cr(VI) species on this sample contributed to high activity toward PDH process. The investigation of the isolated Cr(VI) species is very important for the Cr‐based PDH catalyst system.

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Section: Resultsmentioning

confidence: 99%

Investigation of the Isolated Cr(VI) Species in Cr/MCM‐41 Catalysts and its Effect on Catalytic Activity for Dehydrogenation of Propane

Zhang

Yang

et al. 2018

ChemCatChem

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“…The resulting substance was filtered and washed using deionized water and dried at 110°C for 6 hour in air ambient. Finally, the calcination fulfilled at 600°C in 6 hour and air ambient …”

Section: Methodsmentioning

confidence: 99%

“…For active phase loading, certain amounts of calcium precursor and support (active phase/support = 20 wt%) were mixed in deionized water . The mixture was sonicated for 30 minutes with the power of 90 W. Then, it was dried at 110°C for 6 hours and calcined for 3 hours at 650°C in air ambient.…”

Section: Methodsmentioning

confidence: 99%

“…35,36 For active phase loading, certain amounts of calcium precursor and support (active phase/support = 20 wt%) were mixed in deionized water. 37 The mixture was sonicated for 30 minutes with the power of 90 W. Then, it was dried at 110°C for 6 hours and calcined for 3 hours at 650°C in air ambient. The synthesized nanocatalysts were named Ca/M (Ce = 0), Ca/CeM (Si/Ce = 50), Ca/CeM (Si/Ce = 25), Ca/CeM (Si/Ce = 10), and Ca/CeM (Si/ Ce = 5).…”

Section: Nanocatalysts Preparation and Proceduresmentioning

confidence: 99%

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Structural/texture evolution of CaO/MCM‐41 nanocatalyst by doping various amounts of cerium for active and stable catalyst: Biodiesel production from waste vegetable cooking oil

2019

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Summary In present work, the aim of producing biodiesel from waste cooking oil was pursued by doping the cerium element into the MCM‐41 framework as catalyst with various Si/Ce molar ratio (5, 10, 25, 50, and Ce = 0). The catalytic performance and stability improved by employing the ultrasound irradiation in active phase loading step of catalyst preparation. The physicochemical characteristics of synthesized samples were investigated using various techniques as follows: Brunauer‐Emmett‐Teller (BET), X‐ray powder diffraction (XRD), Fourier transfer infrared (FTIR), energy‐dispersive X‐ray spectroscopy (EDX), transmission electron microscopy (TEM), and field emission scanning electron microscope (FESEM). The XRD patterns along with the results of FTIR and BET analysis revealed the MCM‐41 framework destruction while increasing the Ce content. The FESEM images of the nanocatalysts illustrated a well distribution and uniform morphology for the Ca/CeM (Si/Ce = 25). The particle size and size distribution of the Ca/CeM (Si/Ce = 25) were subsequently determined by TEM and FESEM images. The activity of fabricated nanocatalysts was evaluated by measuring the free acid methyl ester (FAME) content of produced biodiesel. The tests were carried out at constant operational conditions: T = 60°C, catalyst loading = 5 wt%, methanol/oil molar ratio = 9, and 6‐hour reaction time. A superior activity was observed for Ca/CeM (Si/Ce = 25) among other nanocatalysts with 96.8% conversion of triglycerides to biodiesel. The mentioned sample was utilized in five reaction cycles, and at the end of the fifth cycle, the conversion reached to 91.5% which demonstrated its significant stability.

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“…Increased alkane conversion is observed with high Cr 6+ /Cr 3+ ratios, but there is a maximum amount of Cr 6+ that can be added until no further improvement is observed. For example, on the SBA support the maximum loading is 4.3 wt% of Cr 6+ . While Cr‐based catalysts show high initial conversion and selectivity, their implementation is limited due to short lifecycles and high toxicity.…”

Section: Introductionmentioning

confidence: 99%

The effects of bimetallic interactions for CO₂‐assisted oxidative dehydrogenation and dry reforming of propane

2019

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The catalytic reduction of CO 2 by propane may occur via dry reforming to produce syngas (CO + H 2 ) or oxidative dehydrogenation to yield propylene. Utilizing propane and CO 2 as coreactants presents several advantages over conventional methane dry reforming or direct propane dehydrogenation, including lower operating temperatures and less coke formation. Thus, it is of great interest to identify catalytic systems that can either effectively break the C C bond to generate syngas or selectively break C H bonds to produce propylene. In this study, several precious and nonprecious bimetallic catalysts supported on reducible CeO 2 were investigated using flow reactor studies at 823 K to identify selective catalysts for CO 2 -assisted reforming and dehydrogenation of propane. K E Y W O R D SCeO 2 , CO 2 soft oxidant, propane, propylene, synthesis gas | INTRODUCTIONCarbon dioxide management is a prominent issue facing society that requires a diverse portfolio of innovative technologies. High atmospheric concentrations of CO 2 contribute to adverse effects that impact human health and the climate. The need to reduce CO 2 is evident, and the International Panel on Climate Change has stated that climate stabilization (no more than a 2 C rise from preindustrial levels) will require a combination of mitigation, utilization, and even negative emission technologies. 1 Thus, one key approach will be to transform abundant CO 2 into a useful feedstock for processes that not only produce high value products but also match the scale necessary to impact anthropogenic emissions.The two most relevant reactions for the catalytic conversion of CO 2 to CO are reverse water gas shift (RWGS) and dry reforming of methane (DRM). The CO product can be utilized as feedstock for Fischer-Tropsch reactions or methanol synthesis. These two reduction chemistries are not without obstacles, beginning with the challenge that CO 2 is the most thermodynamically stable carbon/oxygen-based molecule (ΔG F = −394 kJ mol −1 ). 2 Current implementation of RWGS has limited feasibility since efforts to obtain large amounts of renewable and CO 2 -free hydrogen are still under development. 3 Furthermore, high coke deposition rates at the reaction temperatures required for DRM hinders further significant improvements in catalyst stability. 4,5 A viable alternative is to utilize other light hydrocarbons, such as ethane or propane, as feedstock for CO 2 reduction. In addition to reforming, these light alkanes contain the C C bond that can be advantageously utilized to build olefins. 6 Thus, the reduction of CO 2 via light alkanes offers two distinct reaction pathways: dry reforming and oxidative dehydrogenation. Specifically, it is of interest to explore the use of propane due to its increasing abundance, competitive pricing, and the demand for propylene, which is one of the most diverse petrochemical building blocks used in the production of various chemicals such as fibers and textiles for a variety of applications.Currently, propylene is primarily coproduced by...

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CO2Oxidative Dehydrogenation of Ethane to Ethylene over Cr/MCM-41 Nanocatalyst Synthesized via Hydrothermal/Impregnation Methods: Influence of Chromium Content on Catalytic Properties and Performance

Cited by 68 publications

References 38 publications

Investigation of the Isolated Cr(VI) Species in Cr/MCM‐41 Catalysts and its Effect on Catalytic Activity for Dehydrogenation of Propane

Investigation of the Isolated Cr(VI) Species in Cr/MCM‐41 Catalysts and its Effect on Catalytic Activity for Dehydrogenation of Propane

Structural/texture evolution of CaO/MCM‐41 nanocatalyst by doping various amounts of cerium for active and stable catalyst: Biodiesel production from waste vegetable cooking oil

The effects of bimetallic interactions for CO₂‐assisted oxidative dehydrogenation and dry reforming of propane

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CO2Oxidative Dehydrogenation of Ethane to Ethylene over Cr/MCM-41 Nanocatalyst Synthesized via Hydrothermal/Impregnation Methods: Influence of Chromium Content on Catalytic Properties and Performance

Cited by 68 publications

References 38 publications

Investigation of the Isolated Cr(VI) Species in Cr/MCM‐41 Catalysts and its Effect on Catalytic Activity for Dehydrogenation of Propane

Investigation of the Isolated Cr(VI) Species in Cr/MCM‐41 Catalysts and its Effect on Catalytic Activity for Dehydrogenation of Propane

Structural/texture evolution of CaO/MCM‐41 nanocatalyst by doping various amounts of cerium for active and stable catalyst: Biodiesel production from waste vegetable cooking oil

The effects of bimetallic interactions for CO2‐assisted oxidative dehydrogenation and dry reforming of propane

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The effects of bimetallic interactions for CO₂‐assisted oxidative dehydrogenation and dry reforming of propane