Effect of process conditions on tar formation from thermal reactions of ethylene

Kaisalo, Noora; Koskinen-Soivi, Mari-Leena; Simell, Pekka; Lehtonen, Juha

doi:10.1016/j.fuel.2015.02.085

Cited by 8 publications

(7 citation statements)

References 29 publications

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“…The main results of all experiments are summarized in Table 1. Ethylene, toluene, and naphthalene conversions were practically complete in all test runs, typical for reforming experiments with the active catalyst at high temperatures and low GHSV of 6000 1/h [6,14,35]. The conditions were similar to the pilot-scale process [5], and therefore the optimal removal of tar and light hydrocarbons was as expected.…”

Section: Conversions and Stabilitiessupporting

confidence: 67%

“…Another interesting aspect of the ethylene content is its relevance as a precursor for PAHs. In our earlier study by Kaisalo et al [14] with the same setup as was used in this study, the thermal tar formation reactions from ethylene were studied at 950 • C, which led to the formation of light components such as methane, propane, 1,3-butadiene, and acetylene, and also to the formation of aromatic compounds with 1-4 rings. In this study, the increasing ethylene concentration did not have any observable effect on the methane, ethylene, or aromatic conversions (Figures 2 and 3, Table 1).…”

Section: Effect Of Ethylene On Carbon Formationmentioning

confidence: 99%

“…At high temperatures, components like ethylene and aromatics begin to react thermally to form solid carbon, especially when in contact with a local hotspot, such as the surface of a catalyst particle or the reactor wall [9,14]. The different pathways to the formation of solid carbon from hydrocarbons have been widely studied, but to summarize on a general level, there are three main routes relevant to this study: (1) decomposition of hydrocarbons and CO to atomic carbon, which begins to form linear polymer intermediates that further combine into aromatic rings [15][16][17]; (2) ethylene reaction to radical light hydrocarbons, which in turn form aromatic rings [18][19][20][21][22][23]; and (3) formation of carbon directly from tar compounds [17,24].…”

Section: Introductionmentioning

confidence: 99%

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Carbon Formation in the Reforming of Simulated Biomass Gasification Gas on Nickel and Rhodium Catalysts

Kihlman

Simell

2022

Catalysts

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Biomass gasification gas contains hydrocarbons that must be converted to CO and H2 prior to the utilization of the gas in a synthesis unit. Autothermal or steam reforming operating with a nickel or noble metal catalyst is a feasible option to treat the gas, but the harsh reaction conditions may lead to the formation of solid carbon. This study discusses the effects of pressure, time-on-stream, and ethylene content on the carbon formation on nickel and rhodium catalysts. The experiments were carried out with laboratory-scale equipment using reaction conditions that were closely simulated after a pilot-scale biomass gasifier. The results indicated that ethylene content above 20,000 vol-ppm and the increased pressure would increase the carbon formation, although there were differences between the rhodium and nickel catalysts. However, carbon formation was significantly more pronounced on the nickel catalyst when the reaction time was increased from 5 h to 144 h. The type of carbon was found to be primarily encapsulating and graphitic. The formation of whisker carbons (also known as carbon nanotubes) was not observed, which is consistent with the literature as the feed gas contained H2S. It was concluded that utilizing a noble metal catalyst as the front layer of the catalyst bed could lower the risk for carbon formation sufficiently to provide stable long-term operation.

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Section: Conversions and Stabilitiessupporting

confidence: 67%

Section: Effect Of Ethylene On Carbon Formationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Carbon Formation in the Reforming of Simulated Biomass Gasification Gas on Nickel and Rhodium Catalysts

Kihlman

Simell

2022

Catalysts

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“…Negative conversions were observed especially at a pressure of 5 bar and lower temperatures due to the thermal formation of the measured tar compounds. Instead of decomposition, tar compounds can be formed in thermal reactions in the presence of lowermolecular-weight tars [33] and ethene [34]. Thus, the amount of the measured component is higher in the reactor outlet than in the inlet.…”

Section: Filters Without a Coatingmentioning

confidence: 99%

Atomic Layer Deposition Coated Filters in Catalytic Filtration of Gasification Gas

et al. 2021

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Steel filter discs were catalytically activated by ALD, using a coating of supporting Al2O3 layer and an active NiO layer for gas cleaning. Prepared discs were tested for model biomass gasification and gas catalytic filtration to reduce or eliminate the need for a separate reforming unit for gasification gas tars and lighter hydrocarbons. Two different coating methods were tested. The method utilizing the stop-flow setting was shown to be the most suitable for the preparation of active and durable catalytic filters, which significantly decreases the amount of tar compounds in gasification gas. A pressure of 5 bar and temperatures of over 850 °C are required for efficient tar reforming. In optimal conditions, applying catalytic coating to the filter resulted in a seven-fold naphthalene conversion increase from 7% to 49%.

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“…4). In an earlier study of thermal for-556 mation of tar from ethene [31] it was observed that ethene forms conditions [29]. In the laboratory-scale tests, the pure olivine A …”

mentioning

confidence: 99%

Effect of pressure on tar decomposition activity of different bed materials in biomass gasification conditions

Tuomi

Kaisalo

Simell

et al. 2015

Fuel

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Effect of process conditions on tar formation from thermal reactions of ethylene

Cited by 8 publications

References 29 publications

Carbon Formation in the Reforming of Simulated Biomass Gasification Gas on Nickel and Rhodium Catalysts

Carbon Formation in the Reforming of Simulated Biomass Gasification Gas on Nickel and Rhodium Catalysts

Atomic Layer Deposition Coated Filters in Catalytic Filtration of Gasification Gas

Effect of pressure on tar decomposition activity of different bed materials in biomass gasification conditions

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