Methanol / Dimethyl Ether Catalytic Transformation Over Zn-modified H-ZSN-5 Zeolite

The universally depleting reserves of traditional hydrocarbons require the development of a technology for producing synthetic hydrocarbons from renewable sources or human waste. Currently, among the possible methods for producing synthetic hydrocarbons, it is necessary to note the Fischer–Tropsch method and the method of methanol / dimethyl ether catalytic transformation. Moreover, the production of synthetic hydrocarbons from synthesis gas — the Fischer–Tropsch method, is suitable for the production of linear hydrocarbons. The hydrocarbons synthesis using methanol / dimethyl ether is suitable for the production of olefins, branched paraffins, aromatic and polyaromatic hydrocarbons. Depending on the synthesis conditions, it is possible to preferentially obtain a certain type of hydrocarbon, which significantly increases the value of this process. In this article modification of zeolite type H-ZSM-5 with zinc is studied in order to increase the yield of liquid hydrocarbons. Zeolite in acid form was treated with zinс acetate solutions of different concentrations, followed by calcination of the samples. The efficiency of the catalysts was studied in a flow tube reactor set-up, and the surface acidity of the samples was also determined. An increase in the zinc content in zeolite contributed to a decrease in the acidity of the samples and modification of their active centers. However, at high zinc content, a separate oxide phase forms, which contributes to a slight increase in acidity. Modification of zeolite with zinc leads to a decrease in the rate of transformation of dimethyl ether and the rate of liquid hydrocarbons formation. However, a general decrease in acidity and modification of zeolite with zinc contributes to a significant decrease in the amount of heavy aromatic compounds formed, with an increase in the amount of gaseous and liquid hydrocarbons being formed.

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In situ H-ZSM-5 Zeolite Deactivation Study in Dimethyl Ether to Hydrocarbons Transformation Reaction

Bulletin of Science and Practice ◽

10.33619/2414-2948/71/01 ◽

2021 ◽

Vol 7 (10) ◽

pp. 10-16

Author(s):

A. Sidorov ◽

Yu. Kosivtsov ◽

R. Brovko ◽

V. Doluda

Keyword(s):

Dimethyl Ether ◽

Aromatic Hydrocarbons ◽

Surface Acidity ◽

Reaction Medium ◽

Sharp Decrease ◽

Weight Percent ◽

Light Olefins ◽

Active Centers ◽

Carbon Deposits

Today, catalytic processes for the synthetic fuel components production are of considerable interest for both scientific and industrial area. The transformation of dimethyl ether into hydrocarbons is one of the possible solutions for the development of a closed hydrocarbon cycle, in connection with which a wide study of this process is an important task of modern catalysis. The transformation of dimethyl ether into hydrocarbons occurs with the formation of heavy polyaromatic hydrocarbons, which are deposited on the surface of active centers, which in turn prevents the further occurrence of chemical processes on their surface. This article presents a study of the deactivation of zeolite H-ZSM-5 by the thermogravimetric method in situ. The results of experiments carried out in the temperature range from to 300 to 400 °C are presented. The accumulation of carbon deposits in the first hour of operation indicates the presence of an induction period due to the formation of the first layer of carbon deposits. Linear decontamination occurs when the first five weight percent of carbon deposits accumulate. Further accumulation of carbon deposits up to eight weight percent leads to a sharp decrease in the rate of conversion of dimethyl ether into hydrocarbons to 0.08 kg (DME) / (kg (Cat) h). In the first hour of operation, aromatic hydrocarbons predominate in the reaction medium; with increasing time, the concentration of aromatic hydrocarbons decreases, and the concentration of light olefins and alkanes increases due to carbonization of the catalyst surface. The concentration of heavy aromatic hydrocarbons with a number of carbon atoms equal to or greater than eleven has a maximum after 240 minutes of reaction. The decrease in the content of heavy aromatic hydrocarbons after 240 minutes of reaction can be explained by the sharp loss of surface acidity due to carbonation.

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Hydroconversion for Hydrocarbon Generation of Highly Overmature Kerogens under Fischer–Tropsch Synthesis Conditions

Energy & Fuels ◽

10.1021/acs.energyfuels.1c00284 ◽

2021 ◽

Author(s):

Kang Li ◽

Hong Lu ◽

Zhongfeng Zhao ◽

Ping’an Peng ◽

Chang Samuel Hsu

Keyword(s):

Tropsch Synthesis ◽

Hydrocarbon Generation ◽

Fischer Tropsch ◽

Fischer Tropsch Synthesis ◽

Synthesis Conditions

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Engineering Modified Mesoporous Silica Catalysts through Porosity and Surface Acidity Control for Selective Production of DME

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.894.45 ◽

2021 ◽

Vol 894 ◽

pp. 45-49

Author(s):

Rosanna Viscardi ◽

Vincenzo Barbarossa ◽

Raimondo Maggi ◽

Francesco Pancrazzi

Keyword(s):

Mesoporous Silica ◽

Dimethyl Ether ◽

Sulfonic Acid ◽

Pore Diameter ◽

Solid Acid ◽

Surface Acidity ◽

High Surface ◽

High Surface Area ◽

Bifunctional Catalysts ◽

Scanning Electronic Microscopy

DME has been received the attention as a renewable energy due to its thermal efficiencies equivalent to diesel fuel, lower NOx emission, near-zero smoke and non-toxic. DME can be obtained by methanol dehydration over solid acid catalysts or directly from syngas over bifunctional catalysts. The catalytic dehydration of methanol to DME has been widely studied in the literature over pure or modified γ -aluminas (γ-Al2O3) and zeolites. Mesoporous silica has obtained much consideration due to its well-defined structural order, high surface area, and tunable pore diameter. In this work, sulfonic acid and aluminium modified mesoporous silica were synthesized and tested as catalysts for production of dimethyl ether from methanol. The modified silicas were studied utilizing XRD, N2 physisorption, pyridine adsorption, and scanning electronic microscopy. The effects of reaction temperature and water deactivation on the methanol selectivity and conversion to dimethyl ether were investigated. Sulfonic acid modified mesoporous silica showed higher selectivity and stability of DME than that of aluminosilicate. The grafting of mesoporous silica with sulfonic groups displayed much more enhanced hydrothermal stability than Al-MCM-41 and γ-Al2O3.

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Evaluation of Recombinant Inbred Lines for Higher Iron and Zinc Content Along with Yield and Quality Parameters in Rice (Oryza sativa L.)

Indian Journal of Agricultural Research ◽

10.18805/ijare.a-5454 ◽

2020 ◽

Author(s):

Maini Bhattacharjee ◽

Kasturi Majumder ◽

Sabyasachi Kundagrami ◽

Tapash Dasgupta

Keyword(s):

Iron Content ◽

Oryza Sativa L ◽

Recombinant Inbred Lines ◽

Zinc Content ◽

Correlation Study ◽

Inbred Lines ◽

Quality Parameters ◽

Fe Content ◽

High Zinc ◽

Iron And Zinc

Rice is one of the most important staple food crops for billions of people throughout the world. It is the cheapest source of dietary energy, protein and minerals for people but poor in micronutrients such as Fe and Zn to eliminate “hidden hunger”. In the present study, a population of 126recombinant inbred lines developed from a cross between Lemont X Satabdi (IET 4786) were used to identify high iron and zinc content coupled with yield and yield attributing traits. Analysis of Variance revealed that a considerable variation in iron and zinc existed among genotypes. The correlation study revealed that number of filled grain was positively associated with panicle length and yield per plant and number of panicles, but no significant positive correlation was observed between grain zinc content and iron content. Zinc and iron content of rice was estimated using Atomic Absorption Spectrophotometer and the samples were prepared by tri-acid digestion method. Among RIL lines, the line 57, 97,120, 48, 99, 124 contained more than 30 ppm Fe and the lines 24, 6, 9, 23, 29, 125 were found to possess more than 50 ppm Zn. The lines 9,6,48 and 57 were recorded to be high yielding with high zinc and Fe content in grain and in future these four lines look promising for multi location trial also. These high Fe and Zn content genotypes can be utilized in future breeding programme as a donor or good source for bio fortification of rice genotypes.

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Metal complexes in catalytic transformation of olefins. 7. Characteristics of active centers and the mechanism of dimerization of ethylene to butene-1 and polymerization of acetylene in the Ti(O-n-Bu)4-AlEt3 catalytic system in ethers

Bulletin of the Russian Academy of Sciences Division of Chemical Science ◽

10.1007/bf00864176 ◽

1992 ◽

Vol 41 (7) ◽

pp. 1175-1182

Author(s):

D. B. Furman ◽

L. N. Russiyan ◽

V. N. Noskova ◽

A. P. Lisitskaya ◽

O. V. Bragin ◽

...

Keyword(s):

Metal Complexes ◽

Catalytic System ◽

Catalytic Transformation ◽

Active Centers

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Effect of acidity on the properties of silica-aluminas synthesized by sol-gel method

Butlerov Communications ◽

10.37952/roi-jbc-01/20-63-7-126 ◽

2020 ◽

Vol 63 (7) ◽

pp. 126-132

Author(s):

Lyubov V. Furda ◽

◽

Evgenia A. Tarasenko ◽

Sofya N. Dudina ◽

Olga E. Lebedeva ◽

...

Keyword(s):

Surface Area ◽

Sol Gel ◽

Molar Ratio ◽

Active Centers ◽

Indicator Method ◽

Synthesis Conditions ◽

Alkaline Conditions ◽

Acidic Conditions ◽

Amphoteric Properties ◽

Hydrolysis Of

In the present work amorphous silica-aluminas were synthesized by the coprecipitation method during the hydrolysis of an alcohol solution of tetraethoxysilane (with a tetraethoxysilane: alcohol mass ratio of 1: 1) and 6% aqueous solution of aluminum nitrate at pH values of 1, 3, and 10. The Si/Al molar ratio for all synthesized samples were 4.72 (± 0.29). The amorphous character of the investigated materials was confirmed by X-ray phase analysis. According to the results of scanning electron microscopy, it was found that the resulting powders have particles with a size of 1-20 μm. It was shown that the conditions of synthesis affected the specific surface area and porosity of the materials under study. By the method of low-temperature adsorption-thermodesorption of nitrogen it was established that silica-aluminas obtained under acidic conditions were microporous materials. For the sample obtained under alkaline conditions (pH = 10), the contribution of macropores is very significant. A decrease in surface area is observed as the pH of the synthesis increases. The Hammett indicator method was used to identify and quantify surface centers of different acidity. All studied silica-aluminas are characterized by the presence of both Brønsted basic (pKax from 7 to 12.8) and acidic (pKax from 0 to 7) centers, and Lewis basic (pKax from -4.4 to 0) with a pronounced maximum at pKax = 1.02. It was found that the synthesis conditions had a significant effect on the concentration of active centers. The values of the Hammett function are practically the same for the 3 studied silica-aluminas and describe the studied samples as materials of medium acidity. The variety of Lewis and Brønsted centers on the surface indicates the amphoteric properties of the materials under study. This gives the samples the properties of polyfunctional sorbents and catalysts.

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