Deactivation and regeneration of Ni catalyst during steam reforming of model biogas: An experimental investigation

Abstract

This paper presents detailed study of biogas reforming. Model biogas with different levels of H 2 S is subjected to reforming reaction over supported Ni catalyst in a fixed bed reactor at 700 o C and 800 o C. In order to understand the poisoning effects of H 2 S the reactions have been initially carried out without H 2 S in the feed stream. Three different H 2 S concentrations (20, 50 and 100 ppm) have been considered in the study. The H 2 O to CH 4 ratio is maintained in such as way that CO 2 also participates in the reforming reaction. After performing the poisoning studies, regeneration of the catalyst has been studied using three different techniques i) removal of H 2 S from the feed stream ii) temperature enhancement and iii) steam treatment. Poisoning at low temperature is not recoverable just by removal of H 2 S from the feed stream. However, poisoning at high temperature is easily reversed just by removal of H 2 S from the feed stream. Unlike some previous reports [1,2], catalyst regeneration is achieved in shorter time frames for all the regeneration techniques attempted.

A detailed kinetic model for biogas steam reforming on Ni and catalyst deactivation due to sulfur poisoning

“…The kinetic model presented in Table 1 is developed by fine tuning the pre-exponential factors to reproduce our own experiments [27]. The only adjustable parameter in the modeling results presented below is A v0 .…”

Catalyst Deactivation and Regeneration Processes in Biogas Tri-Reforming Process. The Effect of Hydrogen Sulfide Addition

“…Among the literature available regarding sulfur deactivation under the biogas steam reforming process, Appari et al studied the deactivation and regeneration of a Ni catalyst during steam reforming of model biogas. These experimental investigations were focused on the activity and regeneration processes of a self-prepared catalyst, obtaining low deactivation curves and successful regeneration process by steam treatment [17]. However, there are no experimental results available, to the best of our knowledge, about the effect of sulfur poisoning operating under a biogas tri-reforming process.…”

Sulfur Poisoning of SOFCs: A Model Based Explanation of Polarization Dependent Extent of Poisoning

“…[5][6][7][8] Most of the experimental literature deals with H 2 S concentrations well below 10 ppm and work that treats H 2 S concentrations higher than 20 ppm is rather limited. 2,5,8 On the other hand it is well known that natural gas and biogas can have substantially higher sulfur concentrations and that catalytic steam reforming of methane can be carried out on Ni even with 100 ppm H 2 S without losing all catalytic activity 9,10 e.g., a methane conversion (in model biogas) of ∼35% can be maintained using a supported Ni catalyst with 100 ppm H 2 S at 800…”

“…• C. 10 For an electrolyte supported cell Zha et al, 2 studied the cell performance for a wide range of H 2 S concentrations using DC polarization and electrochemical impedance spectra. The performance drops were reported for 0.18 ppm to 50 ppm H 2 S in H 2 /H 2 S mixture and they found the cell performance to be recoverable, although not fully, even with 50 ppm H 2 S. A different paper from the same group reported the impedance response of the cell before and after poisoning for galvanostatic and potentiostatic conditions and the maximum H 2 S concentration examined was 10 ppm.…”