The influence of hydrogen on the kinetics of plasmapyrolytic methane conversion

Drost, H.; Klotz, H.-D.; Schulz, Günter; Spangenberg, H.‐J.

doi:10.1007/bf00567909

Cited by 9 publications

(5 citation statements)

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“…Table 1 presents the volumetric concentrations of the inlet and outlet gases during MW plasma treatment for runs with different H 2 :CH 4 ratios. Based on these results, conversion rate, selectivities, and yield were calculated, according to Equations ( 17)- (21). In addition to C 2 H 2 , C 2 H 4 , and hydrogen, another main product was carbonaceous material.…”

Section: Resultsmentioning

confidence: 99%

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Shifts in Product Distribution in Microwave Plasma Methane Pyrolysis Due to Hydrogen and Nitrogen Addition

Wnukowski

Gerber

Mróz

2022

Methane

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Methane pyrolysis can produce many valuable products besides hydrogen, e.g., C2 compounds or carbon black. In the conditions provided by microwave plasma, the distribution of these products might be shifted by the addition of hydrogen and nitrogen. In this work, different ratios of H2:CH4, ranging from 0:1 to 4:1, were tested. The most unambiguous and promising result was obtained for the highest H2:CH4 ratio. For this ratio, a significant improvement in methane conversion rate was observed (from 72% to 95%) along with the increase in C2H2 and C2H4 yield and selectivity. The results support the hypothesis that the H radicals present in the plasma are responsible for improving methane conversion, while the presence of molecular hydrogen shifts the product distribution towards C2 compounds. Based on the carbon balance, the increase in the output of C2 compounds was obtained at the cost of solid carbon. At the same time, the addition of hydrogen resulted in the formation of bigger carbon particles. Finally, with the addition of both nitrogen and hydrogen, the formation of carbon was completely inhibited. Hydrogen cyanide was the main product formed instead of soot and some of the acetylene.

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Section: Resultsmentioning

confidence: 99%

“…In the case of traditional pyrolysis or strictly non-equilibrium plasmas, the observed effect is the opposite-the addition of hydrogen decreases the conversion rate due to reaction reversal of reaction (3), which is favored in temperatures lower than ca. 2000 K [21,22].…”

Section: Introductionmentioning

confidence: 99%

Shifts in Product Distribution in Microwave Plasma Methane Pyrolysis Due to Hydrogen and Nitrogen Addition

Wnukowski

Gerber

Mróz

2022

Methane

View full text Add to dashboard Cite

show abstract

“…This phenomenon can be explained by a high concentration of H radicals (reaching up to 10% [60,61]) and high temperatures in the MW plasma region that affect the reaction R3 (with the reaction rate constant being T 3 dependent) and a subsequent R4 and R5, resulting in a higher conversion rate of methane and its radicals. Secondly, the dilution with hydrogen suppresses the production of benzene and soot by inhibiting the decomposition of acetylene [37,50,62]. As a result, higher selectivity of acetylene is obtained which is usually accompanied by a higher selectivity of ethylene.…”

Section: Reactions Of Methane Conversionmentioning

confidence: 99%

“…It should be noted that this effect was observed in the typical (non-plasma) thermal process of methane decomposition with the temperature range being c.a 1200-2000 K and was accompanied by a decrease in the conversion rate of methane due to reaction reverse to R3. However, this reaction loses its importance in high temperatures (c.a 2500 K) due to the low reaction rate constant [38,62]. Moreover, the effect of soot formation suppression by the presence of hydrogen is also strongly limited in high temperatures [62].…”

Section: Reactions Of Methane Conversionmentioning

confidence: 99%

“…However, this reaction loses its importance in high temperatures (c.a 2500 K) due to the low reaction rate constant [38,62]. Moreover, the effect of soot formation suppression by the presence of hydrogen is also strongly limited in high temperatures [62]. The measured systems were used to determine the rotational and vibrational temperatures.…”

Section: Reactions Of Methane Conversionmentioning

confidence: 99%

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