Effectiveness of biporous catalysts for zero-order reactions
TL;DR: In this article, the authors extended an analysis of zero-order reaction for monoporous catalysts (which has been presented by Weekmann and Gorring) to biporous structures.
About: This article is published in Journal of Catalysis.The article was published on 1992-01-01. It has received 4 citations till now. The article focuses on the topics: Catalysis.
Citations
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TL;DR: A review of the models proposed in the literature is presented together with a critical analysis of assumptions involved in this paper, where the relative significance of macro-and micropore diffusion resistances on the observed reaction rates with linear and nonlinear rate forms, heat effects, catalyst deactivation and selectivity problems in bidisperse catalysts are investigated in number of published works.
Abstract: Catalysts with bidisperse pore structures are extensively used in chemical industries. In such catalysts, diffusion and reaction in the microporous particles are preceded by diffusion in the macropores. The relative significance of macro- and micropore diffusion resistances on the observed reaction rates with linear and nonlinear rate forms, heat effects, catalyst deactivation and selectivity problems in bidisperse catalysts are investigated in number of published works. In this article, a review of the models proposed in the literature is presented together with a critical analysis of assumptions involved. Criteria are presented to test the relative significance of transport limitations. Also, a review of experimental techniques and experimental values of micro- and macropore effective diffusivities of gases in solids with bidisperse pore structures, such as zeolite pellets and supported porous catalysts, is given.
64 citations
TL;DR: In this paper , processed zero valent iron can be pelletised and used to desalinate water, which can also be used for water purification, wastewater desalination, domestic wastewater, treatment of domestic wastewater and treatment of livestock feed water.
Abstract: This study establishes that processed zero valent iron can be pelletised and used to desalinate water. The pellets desalinate water using a zero-order reaction, where: product water salinity = −[a][Reaction Time] + Feed Water Salinity. Desalination using the pellets requires no onsite energy, no onsite infrastructure, and produces no reject brine. Potential applications for the pellets, include desalination of saline impoundments, desalination of agricultural water, desalination of irrigation water, desalination of irrigated salinized soils, and aquifer desalination. The examples demonstrate 30% to 60% desalination for saline feed water within the salinity range of 4 to 10 g L−1. The product water has a low outcome variability for a specific pellet charge. The achievable desalination increases as the pellet weight: water volume ratio increases. The pellets can also be used for water purification, wastewater desalination, treatment of domestic wastewater, treatment of industrial wastewater, treatment of livestock feed water, treatment of oil field and mining wastewater, water purification to allow reuse, and the treatment of polluted soils. This study addresses the manufacture of the pellets, their effectiveness in desalinating water, and the outcome variability associated with desalination.
6 citations
TL;DR: In this article, an algorithm for solving bidispersed catalyst pellet problems is presented, which is a new application of the classical shooting method with Newton correction to a very important class of reaction.
3 citations
01 May 2023
TL;DR: In this paper , a continuous flow of a synthetic, dry, and acidic waste synthesis gas (WSG) (containing N2, H2, CO, CH4, and CO2) at ambient temperatures was first passed through a fixed bed reactor (FBR) containing halite + m-Fe0 and then a saline bubble column diffusion reactor (BCDR) containing m- Fe0.
Abstract: In this study, a continuous flow of a synthetic, dry, and acidic waste synthesis gas (WSG) (containing N2, H2, CO, CH4, and CO2) at ambient temperatures was first passed through a fixed bed reactor (FBR) containing halite + m-Fe0 and then a saline bubble column diffusion reactor (BCDR) containing m-Fe0. The FBR converted 47.5% of the CO + CH4 + CO2 into n-C0. Passage of the n-C0 into the BCDR resulted in the formation of the desalination catalyst (Fe0:Fe(a,b,c)@C0) + CH4 + CO + CO2 + CxHy, where 64% of the feed n-C0 was converted to gaseous products. The desalination pellets can remove >60% of the water salinity without producing a reject brine or requiring an external energy source. The gaseous products from the BCDR included: CxHy (where x < 6), CO, CO2, and H2.
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TL;DR: In this article, an equation for the effectiveness factor for an isothermal first-order reaction taking place in a bidisperse spherical catalyst pellet has been derived, which shows the dependence of this factor on the magnitude of a parameter, which depends mainly on the ratio of diffusion times in the macro and micropore regions and on the Thiele modulus.
Abstract: An equation for the effectiveness factor for an isothermal first-order reaction taking place in a bidisperse spherical catalyst pellet has been derived, which shows the dependence of this factor on the magnitude of a parameter ..cap alpha.., which depends mainly on the ratio of diffusion times in the macro and micropore regions and on the Thiele modulus. For most practical catalysts, the value of ..cap alpha.. lies between 1 and 1000. The ratio of effectiveness factor values determined by the present model and by the conventional method for monodisperse catalysts, which method is based only on the Thiele modulus, increased from 0.74:1 at ..cap alpha.. = 1 to 0.92:1 at ..cap alpha.. = 1000. At a fixed value of ..cap alpha.., the ratio decreases as the Thiele modulus increases. The present approach can also be applied to nonisothermal systems and to other pellet geometries.
30 citations
16 citations