Niobia-alumina as methanol dehydration component in mixed catalyst systems for dimethyl ether production from syngas

Lima, Stevie H.; Forrester, Aline M.S.; Palacio, Luz Amparo; Faro, Arnaldo C.

doi:10.1016/j.apcata.2014.09.022

Cited by 21 publications

(13 citation statements)

References 39 publications

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“…A progressive decrease in the intensity of the surface hydroxyl negative bands is observed by increasing the temperature which indicates a partial restoration of hydroxyl groups on the alumina surface 9,29 . This is due to the desorption of some of the adsorbed methoxy species that form hydrogen bonds with these hydroxyl groups which is confirmed by the accompanying decrease in the intensity of the bands at 3260 and 2600 cm -1 .In addition, bands at 1599, 1390 and 1375 cm -1 corresponding to surface formate species started to appear at 200°C and became more intense by increasing the temperature up to 250°C 9,29,[33][34] . Apart from the observed decrease in the intensity of some bands and the increase in the intensity of the others, there is no notable change in the band positions can be observed as temperature increases.…”

Section: Catalyst Activitymentioning

confidence: 95%

Silver-Modified η-Al₂O₃ Catalyst for DME Production

et al. 2017

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Herein, an in-situ DRIFT technique was used to study the reaction mechanism of methanol dehydration to dimethyl ether (DME). Moreover, the effect of silver loading on the catalytic performance of η-Al2O3 was examined in a fixed bed reactor under the reaction conditions where the temperature ranged from 180-300 °C with a WHSV= 48.4 h-1. It was observed that the optimum Ag loading was found to be 10% Ag/η-Al2O3 with this novel catalyst also showing a high degree of stability under steady-state conditions and this is attributed to the enhancement in both the surface Lewis acidity and hydrophobicity.

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Section: Catalyst Activitymentioning

confidence: 95%

Silver-Modified η-Al₂O₃ Catalyst for DME Production

et al. 2017

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“…Dimethyl ether (DME) is gaining considerable attention worldwide as a cleaner fuel because of its environmentally benign fuel properties [1][2]. DME is a colorless gas (at STP) and can be liquefied at about 6 atm at 25 °C, which allows its usage on the same platform of current LPG storage and distribution technologies with minor modifications [3].…”

Section: Introductionmentioning

confidence: 99%

Direct synthesis of dimethyl ether from syngas over Cu-based catalysts: Enhanced selectivity in the presence of MgO

Asthana

Samanta

Bhaumik

et al. 2016

Journal of Catalysis

108

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Direct synthesis of dimethyl ether (DME) from syn-gas was investigated over a series of hybrid catalytic systems containing Cu-based methanol synthesis component with varying amount of ZnO and MgO, and -Al 2 O 3 as a methanol dehydration component. Methanol synthesis and methanol dehydration components were homogeneously mixed in 2:1 weight ratio to prepare the hybrid catalysts, which were characterized by Transmission electron microscopy, Scanning electron microscopy, BET surface area analyzer, Powder X-Ray diffraction, NH 3-Temperature programmed desorption and H 2-Temperature programmed reduction methods. Syn-gas to DME (STD) reaction was studied in an isothermal fixed bed reactor at 30 bar and 260 C. The catalysis results revealed an improved effectiveness of the catalyst in the presence of 20 mol% MgO, enabling a significant enhancement in CO conversion from 19 to 37% and DME selectivity from 36 to 83%, when compared with the activity of a catalyst without MgO. By-products, CO 2 and C 1-C 2 hydrocarbons, selectivity were also decreased from 48 to 14% for CO 2 and from 8 to 2.5% for hydrocarbons. Catalyst performance, CO conversions and DME selectivity were evaluated by varying the reaction temperature, pressure, space velocity and H 2 /CO ratio in syn-gas. XRD data revealed the formation of a well crystalline malachite structure for the catalysts containing up to 20 mol% MgO, but the crystallinity in the structure lost when 30% MgO was added, resulting in a decreased catalytic activity.

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“…8 It is therefore necessary to find a balance between surface basicity and acidity, achieved through optimizing the niobium content. Similarly, it has been reported that physical mixing of Cu-catalysts with γ-Al 2 O 3 affords DME as a major product.…”

Section: ■ Introductionmentioning

confidence: 99%

Hydrogenation of CO₂ to Dimethyl Ether over Brønsted Acidic PdZn Catalysts

Bahruji

Armstrong

Esquius

et al. 2018

Ind. Eng. Chem. Res.

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Eschewing the common trend toward use of catalysts composed of Cu, it is reported that PdZn alloys are active for CO 2 hydrogenation to oxygenates. It is shown that enhanced CO 2 conversion is achievable through the introduction of Brønsted acid sites, which promote dehydration of methanol to dimethyl ether. We report that deposition of PdZn alloy nanoparticles onto the solid acid ZSM-5, via chemical vapor impregnation affords catalysts for the direct hydrogenation of CO 2 to DME. This catalyst shows dual functionality; catalyzing both CO 2 hydrogenation to methanol and its dehydration to dimethyl in a single catalyst bed, at temperatures of >270°C. A physically mixed bed comprising 5% Pd 15% Zn/TiO 2 and H-ZSM-5 shows a comparably high performance, affording a dimethyl ether synthesis rate of 546 mmol kg cat −1 h −1 at a reaction temperature of 270°C . ■ INTRODUCTIONMethanol is ubiquitous within the chemical industry, with global demand exceeding 57 Mt/annum. The majority of this is met through a two-step process whereby synthesis gas is produced via methane steam reforming and then reacted over a Cu/ZnO/Al 2 O 3 catalyst to prepare methanol. The energy consumption of this process is estimated to exceed 1 exajoule (1 × 10 18 J)/annum globally, with a significant carbon footprint (ca. 88 Mt GHG eq). 1 In line with political and social pressure to decrease society's dependence on fossil fuels, there is growing interest in producing methanol through more sustainable routes. One promising route is catalytic CO 2 hydrogenation. The process, however, is restricted by thermodynamic equilibrium; with the reverse water gas shift reaction (RWGS) dominating the reaction at high temperatures. Indeed, methanol is thermodynamically favored at lower temperatures. Unfortunately, because of the relatively low reactivity of CO 2 , high reaction temperatures and/or pressures are required for its activation. To maximize yields of valueadded products, it is important that CO 2 hydrogenation be carried out near equilibrium. One approach toward circumventing RWGS at elevated reaction temperatures is removal of the product, methanol, from the catalytic system. This can be achieved through dehydration to dimethyl ether (DME), typically over a solid acid catalyst. DME is a key feedstock for production of methylating agents for organic synthesis. 2 DME has also been identified as an environmentally friendly fuel, with low associated emissions of NO x , hydrocarbons, CO and SO x . 3 Through the methanol to gasoline (MTG) process, methanol is catalytically converted to yield an equilibrium mixture containing methanol, DME and water. This is then converted to hydrocarbons. 4 Being both exothermic and reversible, methanol dehydration is subject to thermodynamic limitation, though effectively not so under methanol synthesis conditions. 4 Integrating methanol dehydration into CO 2 hydrogenation reaction systems might increase hydrogenation yields, by intercepting the methanol through dehydration to DME, therefore shifting the reactio...

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Niobia-alumina as methanol dehydration component in mixed catalyst systems for dimethyl ether production from syngas

Cited by 21 publications

References 39 publications

Silver-Modified η-Al₂O₃ Catalyst for DME Production

Silver-Modified η-Al₂O₃ Catalyst for DME Production

Direct synthesis of dimethyl ether from syngas over Cu-based catalysts: Enhanced selectivity in the presence of MgO

Hydrogenation of CO₂ to Dimethyl Ether over Brønsted Acidic PdZn Catalysts

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Niobia-alumina as methanol dehydration component in mixed catalyst systems for dimethyl ether production from syngas

Cited by 21 publications

References 39 publications

Silver-Modified η-Al2O3 Catalyst for DME Production

Silver-Modified η-Al2O3 Catalyst for DME Production

Direct synthesis of dimethyl ether from syngas over Cu-based catalysts: Enhanced selectivity in the presence of MgO

Hydrogenation of CO2 to Dimethyl Ether over Brønsted Acidic PdZn Catalysts

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Product

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Silver-Modified η-Al₂O₃ Catalyst for DME Production

Silver-Modified η-Al₂O₃ Catalyst for DME Production

Hydrogenation of CO₂ to Dimethyl Ether over Brønsted Acidic PdZn Catalysts