Microstructured catalytic hollow fiber reactor for methane steam reforming

Microstructured alumina hollow fibers, which contain a plurality of radial microchannels with significant openings on the inner surface, have been fabricated in this study and used to develop an efficient catalytic hollow fiber reactor. Apart from low mass-transfer resistance, a unique structure of this type facilitates the incorporation of Ni-based catalysts, which can be with or without the aged secondary support, SBA-15. In contrast to a fixed bed reactor, the catalytic hollow fiber reactor shows similar methane conversion, with a gas hourly space velocity that is approximately 6.5 times higher, a significantly greater CO2 selectivity, and better productivity rates. These results demonstrate the advantages of dispersing the catalyst inside the microstructured hollow fiber as well as the potential to reduce the required quantity of catalyst

Techno-economic assessment of membrane assisted fluidized bed reactors for pure H2 production with CO2 capture

This paper addresses the techno-economic assessment of two membrane-based technologies for H2 production from natural gas, fully integrated with CO2 capture. In the first configuration, a fluidized bed membrane reactor (FBMR) is integrated in the H2 plant: the natural gas reacts with steam in the catalytic bed and H2 is simultaneously separated using Pd-based membranes, and the heat of reaction is provided to the system by feeding air as reactive sweep gas in part of the membranes and by burning part of the permeated H2 (in order to avoid CO2 emissions for heat supply). In the second system, named membrane assisted chemical looping reforming (MA-CLR), natural gas is converted in the fuel rector by reaction with steam and an oxygen carrier (chemical looping reforming), and the produced H2 permeates through the membranes. The oxygen carrier is re-oxidized in a separate air reactor with air, which also provides the heat required for the endothermic reactions in the fuel reactor. The plants are optimized by varying the operating conditions of the reactors such as temperature, pressures (both at feed and permeate side), steam-to-carbon ratio and the heat recovery configuration. The plant design is carried out using Aspen Simulation, while the novel reactor concepts have been designed and their performance have been studied with a dedicated phenomenological model in Matlab. Both configurations have been designed and compared with reference technologies for H2 production based on conventional fired tubular reforming (FTR) with and without CO2 capture. The results of the analysis show that both new concepts can achieve higher H2 yields than conventional plants (12-20% higher). The high electricity consumptions of membrane-based plants are associated with the required low pressure at the retentate side. However, the low energy cost for the CO2 separation and compression makes the overall reforming efficiency from 4% to 20% higher than conventional FTR with CO2 scrubbing. FBMR and MA-CLR show better performance than FTR with CO2 capture technology in terms of costs mainly because of lower associated CAPEX. The cost of H2 production reduces from 0.28 €/NmH23 to 0.22 €/NmH23 (FBMR) and 0.19 €/NmH23 (MA-CLR)

Autothermal reforming of palm empty fruit bunch bio-oil: thermodynamic modelling

This work focuses on thermodynamic analysis of the autothermal reforming of palm empty fruit bunch (PEFB) bio-oil for the production of hydrogen and syngas. PEFB bio-oil composition was simulated using bio-oil surrogates generated from a mixture of acetic acid, phenol, levoglucosan, palmitic acid and furfural. A sensitivity analysis revealed that the hydrogen and syngas yields were not sensitive to actual bio-oil composition, but were determined by a good match of molar elemental composition between real bio-oil and surrogate mixture. The maximum hydrogen yield obtained under constant reaction enthalpy and pressure was about 12 wt% at S/C = 1 and increased to about 18 wt% at S/C = 4; both yields occurring at equivalence ratio Φ of 0.31. The possibility of generating syngas with varying H2 and CO content using autothermal reforming was analysed and application of this process to fuel cells and Fischer-Tropsch synthesis is discussed. Using a novel simple modelling methodology, reaction mechanisms were proposed which were able to account for equilibrium product distribution. It was evident that different combinations of reactions could be used to obtain the same equilibrium product concentrations. One proposed reaction mechanism, referred to as the ‘partial oxidation based mechanism’ involved the partial oxidation reaction of the bio-oil to produce hydrogen, with the extent of steam reforming and water gas shift reactions varying depending on the amount of oxygen used. Another proposed mechanism, referred to as the ‘complete oxidation based mechanism’ was represented by thermal decomposition of about 30% of bio-oil and hydrogen production obtained by decomposition, steam reforming, water gas shift and carbon gasification reactions. The importance of these mechanisms in assisting in the eventual choice of catalyst to be used in a real ATR of PEFB bio-oil process was discussed

Investigations on hydrogenation of selected organic sulfur compounds on the Ni-Mo/Al2O3 catalyst in terms of natural gas desulfurization

Technological problems of natural gas desulfurization in syngases manufacturing plants have been discussed and the results of investigations on the activity of the model Ni-Mo/Al$\text{}_{2}$O$\text{}_{3}$ catalyst in hydrogenation of selected sulfur compounds have been presented. The HDS reaction rate is dependent on a compound structure. The hydrogenation rate on the Ni-Mo/Al$\text{}_{2}$O$\text{}_{3}$ catalyst for the given sulfur compound increases in the order: CS$\text{}_{2}$(CH$\text{}_{3}$)$\text{}_{2}$S>C$\text{}_{4}$H$\text{}_{10}$S>C$\text{}_{2}$H$\text{}_{6}$S$\text{}_{2}$C$\text{}_{4}$H$\text{}_{4}$S

Study of the viscosity of hydrocarbon mixtures under pressure and temperature: A critical model of the corresponding states to double reference in the modeling domain.

ACTInternational audienceThe studied predictive model of behavior viscosimetric is the model of K.A. Petersen [1]. The dominant idea of this method is to characterize the viscosity of a fluid from two models taken as a reference in passing through a reduced pressure. The method is corresponding state with two references. This study shows that this method is dependent on the choice of reference and for each of the possibilities of C10/C6H6 and C1/C10 references . The results were investigated for four different weight ratios. It shows that the introduction of an adjusted coefficient does not improve significantly compared to results without adjustment factor, which appears to be the best choice. Regarding the influence of the choice of references, generally the two couples appear suitable but we noted that the choice is not necessary. In the case of mixtures containing at least one aromatic, the results are correct, especially if one takes the ratio of adjustment and our ratio without adjustment compared to that of K. A. PETERSEN[1]. The experimental results of the viscosity exhibit a good agreement with the calculated values. We can predict that the relative improvement is the finding that the introduction of the second body of reference (C10) from the model states corresponding to a reference (C1) of the authors. © Published under licence by IOP Publishing Ltd