scholarly journals Process Intensification of the Propane Dehydrogenation Considering Coke Formation, Catalyst Deactivation and Regeneration—Transient Modelling and Analysis of a Heat-Integrated Membrane Reactor

Catalysts ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1056
Author(s):  
Jan P. Walter ◽  
Andreas Brune ◽  
Andreas Seidel-Morgenstern ◽  
Christof Hamel

A heat-integrated packed-bed membrane reactor is studied based on detailed, transient 2D models for coupling oxidative and thermal propane dehydrogenation in one apparatus. The reactor is structured in two telescoped reaction zones to figure out the potential of mass and heat integration between the exothermic oxidative propane dehydrogenation (ODH) in the shell side, including membrane-assisted oxygen dosing and the endothermic, high selective thermal propane dehydrogenation (TDH) in the inner core. The developing complex concentration, temperature and velocity fields are studied, taking into account simultaneous coke growth corresponding with a loss of catalyst activity. Furthermore, the catalyst regeneration was included in the simulation in order to perform an analysis of a periodic operating system of deactivation and regeneration periods. The coupling of the two reaction chambers in a new type of membrane reactor offers potential at oxygen shortage and significantly improves the achievable propene yield in comparison with fixed bed and well-established membrane reactors in the distributor configuration without inner mass and heat integration. The methods developed allow an overall process optimization with respect to maximum spacetime yield as a function of production and regeneration times.

2017 ◽  
Vol 42 (4) ◽  
pp. 344-360
Author(s):  
Milad Komasi ◽  
Shohreh Fatemi ◽  
Seyed Hesam Mousavi

Pt–Sn/hierarchical SAPO-34 was synthesised and kinetically modelled as an efficient and selective catalyst for propylene production through propane dehydrogenation. The kinetics of the reaction network were studied in an integral fixed-bed reactor at three temperatures of 550, 600 and 650 °C and weight hourly space velocities of 4 and 8 h−1 with a feed containing hydrogen and propane with relative molar ratios of 0.2, 0.5 and 0.8, at normal pressure. The experiments were performed in accordance with the full factorial experimental design. The kinetic models were constructed on the basis of different mechanisms and various deactivation models. The kinetics and deactivation parameters were simultaneously predicted and optimised using genetic algorithm optimisation. It was further proven that the Langmuir–Hinshelwood model can well predict propane dehydrogenation kinetics through lumping together all the possible dehydrogenation steps and also by assuming the surface reaction as the rate-determining step. A coke formation kinetic model has also shown appropriate results, confirming the experimental data by equal consideration of both monolayer and multilayer coke deposition kinetic orders and an exponential deactivation model.


Author(s):  
Christof Hamel ◽  
Michael Bron ◽  
Peter Claus ◽  
Andreas Seidel-Morgenstern

The hydrogenation of acrolein was investigated experimentally in a fixed-bed reactor (FBR) using several classical and a newly developed hydrogenation catalyst. The aim was to evaluate selectivity and yield with respect to the desired product allyl alcohol. The kinetics of the two main parallel reactions of acrolein hydrogenation were quantified for a supported silver catalyst which offered the highest performance. In a second part the reaction kinetics identified were used in a theoretical study applying a simplified isothermal 1D reactor model in order to analyse the hydrogenation of acrolein performed in single- and multi-stage packed bed membrane reactors (PBMR). The goal of the simulations was to evaluate the potential of dosing one reactant in a distributed manner using one or several membrane reactor stages. The results achieved indicate that the membrane reactor concept possesses the potential to provide improved yields of allyl alcohol compared to conventional co-feed fixed-bed operation.


Catalysts ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1374
Author(s):  
Andreas Brune ◽  
Andreas Seidel-Morgenstern ◽  
Christof Hamel

This study intends to provide insights into various aspects related to the reaction kinetics of the VOx catalyzed propane dehydrogenation including main and side reactions and, in particular, catalyst deactivation and regeneration, which can be hardly found in combination in current literature. To kinetically describe the complex reaction network, a reduced model was fitted to lab scale experiments performed in a fixed bed reactor. Additionally, thermogravimetric analysis (TGA) was applied to investigate the coking behavior of the catalyst under defined conditions considering propane and propene as precursors for coke formation. Propene was identified to be the main coke precursor, which agrees with results of experiments using a segmented fixed bed reactor (FBR). A mechanistic multilayer-monolayer coke growth model was developed to mathematically describe the catalyst coking. Samples from long-term deactivation experiments in an FBR were used for regeneration experiments with oxygen to gasify the coke deposits in a TGA. A power law approach was able to describe the regeneration behavior well. Finally, the results of periodic experiments consisting of several deactivation and regeneration cycles verified the long-term stability of the catalyst and confirmed the validity of the derived and parametrized kinetic models for deactivation and regeneration, which will allow model-based process development and optimization.


Author(s):  
William Andrés Mejía Galarza ◽  
Javier Herguido Huerta ◽  
Miguel Alejandro Menéndez Sastre

Methanol is considered to be a potential energy carrier. Currently, its synthesis from CO2 is performed in conventional reactors, although its yield can be improved if a packed bed membrane reactor (PBMR) is used instead. The objective of this work is to select potential PBMRs as an alternative to the conventional ones.


Energies ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 53
Author(s):  
Kai Miao ◽  
Tan Li ◽  
Jing Su ◽  
Cong Wang ◽  
Kaige Wang

Catalytic hydropyrolysis via the introduction of external hydrogen into catalytic pyrolysis process using hydrodeoxygenation catalysts is one of the major approaches of bio-oil upgrading. In this study, hydrodeoxygenation of acetone over Mo/HZSM-5 and HZSM-5 were investigated with focus on the influence of hydrogen pressure and catalyst deactivation. It is found that doped MoO3 could prolong the catalyst activity due to the suppression of coke formation. The influence of hydrogen pressure on catalytic HDO of acetone was further studied. Hydrogen pressure of 30 bar effectively prolonged catalyst activity while decreased the coke deposition over catalyst. The coke formation over the HZSM-5 and Mo/HZSM-5 under 30 bar hydrogen pressure decreased 66% and 83%, respectively, compared to that under atmospheric hydrogen pressure. Compared to the test with the HZSM-5, 35% higher yield of aliphatics and 60% lower coke were obtained from the Mo/HZSM-5 under 30 bar hydrogen pressure. Characterization of the spent Mo/HZSM-5 catalyst revealed the deactivation was mainly due to the carbon deposition blocking the micropores and Bronsted acid sites. Mo/HZSM-5 was proved to be potentially enhanced production of hydrocarbons.


2018 ◽  
Vol 6 (3) ◽  
pp. 666
Author(s):  
Azis Trianto ◽  
Ira Santrina J C ◽  
Susilo Yuwono

Hydrogen is a promising alternative fuel to establish environmentally friendly energy generation system. One of the methods for producing hydrogen is C02 methane reforming (CMR) process. Despite producing H2, this process also consumes CO2 enabling it to be used as a scheme for mitigating CO2. Conventionally, the hydrogen production via CMR is conducted in a fixed bed reactor. However low conversion is usually found in this kind of reactor. To increase conversion, a membrane reactor can be used. Two types of membrane may be employed to conduct this reaction, i.e. prorous  vycor and nanosil membrane  reactor.  This study  evaluated the  performances  of CMR con 1ucted in membrane ractors andfixed-bed reactor. The results show that the conversion obtained in nanosil membrane reactor is higher than those obtained in porous vycor membrane reactor and fixed-bed reactor. With the change in reactant flowrate, it is obtained that the conversions in membrane reactors are more stable than those infixed bed reactors.Keywords: Hydrogen Production, Membrane Reactor, Methane Reforming AbstrakHidrogen merupakan bahan bakar alternatif yang sangat menjanjikan untuk sistem pembangkitan energi yang lebih ramah lingkungan. Salah satu rute produksi hidrogen adalah melalui reformasi metana dengan karbondioksida (C02 Methane Reforming/CMR). Saat ini telah dikembangkan proses CMR menggunakan membran yang mampu meningkatkan laju produksi H2• Pada makalah ini dikaji dua tipe reaktor membran untuk maksud peningkatan produksi hidrogen tersebut, yakni reaktor membran dengan basis membran porous vycor dan nanosil. Sebagai pembanding, dilakukanjuga evaluasi unjuk kerja reaksi CMRpada reaktorfzxe-bed. Hasil kajian ini menurljukkan bahwa reaktor nanosil danporous vycor mampu memberikan konversiyang lebih besar dibanding reaktor fixed-bed. Lebihjauh, reaktor membran dengan nanosil membran mampu memberikan laju produksi hidrogen yang lebih tinggi dibanding reaktor membran dengan membran porous vycor. Lebih jauh, pada perubahan laju molar reaktan, reaktor membran menurijukkan stabilitas yang lebih baik dibanding reaktor fixed-bed.Kata Kunci: Produksi Hidrogen, Reaktor Membran, Reformasi Metana


1989 ◽  
Vol 54 (2) ◽  
pp. 375-387 ◽  
Author(s):  
Jozef Markoš ◽  
Alena Brunovská

In this paper the influence of the active catalyst location in a pellet on fixed-bed catalytic reactor performance is described. The optimal activity distribution as a function of an economic parameter (ratio of product and catalyst costs), Thiele modulus and Damkohler number is estimated.


AIChE Journal ◽  
1993 ◽  
Vol 39 (3) ◽  
pp. 526-529 ◽  
Author(s):  
Z. D. Ziaka ◽  
R. G. Minet ◽  
T. T. Tsotsis

2019 ◽  
Vol 35 (3) ◽  
pp. 377-392 ◽  
Author(s):  
Majid Taghizadeh ◽  
Fatemeh Aghili

AbstractDuring the last decade, hydrogen has attracted lots of interest due to its potential as an energy carrier. Ethanol is one of the renewable resources that can be considered as a sustainable candidate for hydrogen generation. In this regard, producing hydrogen from ethanol steam reforming (ESR) would be an environmentally friendly process. Commonly, ESR is performed in packed bed reactors; however, this process needs several stages for hydrogen separation with desired purity. Recently, the concept of a membrane reactor, an attractive device integrating catalytic reactions and separation processes in a single unit, has allowed obtaining a smaller reactor volume, higher conversion degrees, and higher hydrogen yield in comparison to conventional reactors. This paper deals with recent advances in ESR in terms of catalyst utilization and the fundamental of membranes. The main part of this paper discusses the performance of different membrane reactor configurations, mainly packed bed membrane reactors, fluidized bed membrane reactors, and micro-membrane reactors. In addition, a short overview is given about the impact of ESR via different catalysts such as noble metal, non-noble metal, and bi-metallic catalysts.


Membranes ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 152 ◽  
Author(s):  
Aitor Cruellas ◽  
Wout Ververs ◽  
Martin van Sint Annaland ◽  
Fausto Gallucci

Novel reactor configurations for the oxidative coupling of methane (OCM), and in particular membrane reactors, contribute toward reaching the yield required to make the process competitive at the industrial scale. Therefore, in this work, the conventional OCM packed bed reactor using a Mn-Na2WO4/SiO2 catalyst was experimentally compared with a membrane reactor, in which a symmetric MgO porous membrane was integrated. The beneficial effects of distributive feeding of oxygen along the membrane, which is the main advantage of the porous membrane reactor, were demonstrated, although no significant differences in terms of performance were observed because of the adverse effects of back-permeation prevailing in the experiments. A sensitivity analysis carried out on the effective diffusion coefficient also indicated the necessity of properly tuning the membrane properties to achieve the expected promising results, highlighting how this tuning could be addressed.


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