Comparison of Catalysts in the Point of View of Pellet Stove Flue Gas Purification

Monolithic catalysts are used as a method for the flue gases purifying by oxidation of gas products from incomplete combustion. This study is focused on three different types of monolithic catalysts and quantification of their degree of influence on mass concentration of carbon monoxide (CO) and organic gaseous compounds (OGCs) in real small-scale wood pellet stove. Catalysts were placed right behind the stove at the flue gas outlet. The comparison consisted of quantification of their influence on the selected pollutants during the few-hours steady operation of the small-scale pellet stove. Reference values of the selected pollutants were defined during the combustion test without a catalyst installed. In this article, three catalysts based on different active compounds: WO3–V2O5, Pd and Pt were tested. The palladium-based catalyst has proven the best degree of conversion of CO (almost 78%). The platinum-based catalyst has proven the best degree of conversion of OGC (almost 64%). Due to a big degree of clogging by solid particles of all catalysts during the tests, it is impossible to operate the chosen stove with tested types of catalysts in normal operation at home conditions. Without any type of periodical cleaning (every few hours), there is a serious danger of leakage of the flue gas out of the stove. Further investigations should evaluate the degree of clogging in a long-term operation and should propose a method to avoid any danger of the flue gas leaking caused by the catalysts.This article was prepared within OP RDE, the project ‘Research on the identification of combustion of unsuitable fuels and systems of self-diagnostics of boilers combusting solid fuels for domestic heating’, identification code CZ.02.1.01/0.0/0.0/18_069/0010049, with the financial support from the European Regional Development Fund. This article was also prepared within the project SP2019/83 ‘Monitoring the operating parameters of a small combustion equipment and determining its effect on condensation of water in the flue gas’ and was elaborated in the framework of the grant program ‘Support for Science and Research in the Moravia-Silesia Region 2018’, (RRC/10/2018), financed from the budget of the Moravian-Silesian Region

Beech Leaves Briquettes’ and Standard Briquettes’ Combustion: Comparison of Flue Gas Composition

Biomass stoves are not only popular, widespread and important sources of heat but are also not negligible sources of pollutants. The present study had two objectives in this field of research. The first one was to determine the difference between standard wooden and beech leaves briquettes flue gas composition during similar, standard home combustion conditions. The second objective was to determine the possibility of decreasing the mass concentration of pollutants contained in the flue gas produced by standard and alternative fuel combustion, i.e. wooden briquettes and beech leaves briquettes, by an oxidation catalyst. Significantly higher mass concentration of nitrogen oxides (NOx), almost 2.5 times higher, in the flue gas was observed during the beech leaves combustion. Both fuels reached the edge of actual legislation limit (European Standard Commission regulation [EU] 2015/1185) in case of mass concentration of carbon monoxide (CO). This issue was solved by a palladium-based catalyst with average degree of conversion around 82%. The catalyst also influences flue gas composition from mass concentration of propane point of view with average degree of conversion around 15%. The mass fraction of sulphur, occurring in the beech leaves briquettes, did not cause any issue to the catalyst in terms of its degree of CO conversion. Due to the test results from the beech leaves briquettes, i.e. high mass fraction of ash and high mass concentration of NOx in the flue gas, it is appropriate to use this kind of fuel as secondary fuel during the co-combustion process.This work was supported by the Doctoral grant competition VŠB TU-Ostrava, reg. no. CZ.0 2.2.69/0.0./0.0/19_073/0016945 within the Operational Programme Research, Development and Education, under project DGS/TEAM/2020-035 "Determination of oxidation catalysts characteristics during the flue gas purification"

Catalytic Activity of Cobalt Impregnated on Ordered Mesoporous Silica Materials in N2O Decomposition.

Three different ordered mesoporous silica materials, such as MCM-41, Al containing MCM-41 (mass ratio Si/Al = 10) and SBA-15, were prepared. In a next step, cobalt (5-8 wt%) as an active metal for redox reactions, was introduced by the impregnation. The prepared catalysts were characterized by AAS, EDX, N-2 physisorption, XRD, DR UV-Vis spectroscopy, Raman spectroscopy, TPR-H-2 and their catalytic properties were evaluated for N2O decomposition and reduction. The catalysts showed poor activity in N2O decomposition while the use of reducing agent (carbon monoxide) was beneficial for their catalytic activities. The lowest catalytic activity showed Co/Al-MCM indicating that the aggregated CoxOy species present in this catalyst were inactive and not beneficial for the catalytic activity

The balancing of NO concentration fluctuations by adsorption/desorption process on activated carbon

The present work deals with adsorption/desorption process of NO on activated carbon. The goal of the experiments was to determine under which conditions is the activated carbon bed able to damp down the concentration fluctuations of NO in the gas entering the bed. It was found out that the residence time necessary to balance out the input concentration fluctuations of NO increases along with the average concentration of NO. The minimum mean residence time of 3–9 min was found as necessary to level the average NO concentration ranging from 357 to 1428 ppm. The decisive parameters for the extent of attenuation are discussed in the terms of linear driving force model for fixed-bed adsorber dynamics