Demonstration and Characterization of Ni/Mg/K/AD90 Used for Pilot-Scale Conditioning of Biomass-Derived Syngas

Abstract

A fluidizable, Ni/Mg/K/AD90(90% a-Al 2 O 3 ) catalyst was evaluated in a pilot-scale study with oakderived syngas for tar and methane reforming at 900°C. The catalyst was operated in a semi-batch mode for ten individual reaction cycles, each separated by a regeneration protocol consisting of steaming followed by H 2 reduction. During the experiment, subsequent reaction cycles showed a decrease in activity as indicated by decreased initial methane conversion. During each reaction cycle, H 2 S poisoning was the dominant deactivation mechanism, while coking was deemed to be minor in comparison. Catalyst characterization by XRD and TPR suggest that the loss of activity for subsequent reaction cycles coincides with the formation of a NiAl 2 O 4 species that is not fully reduced under process conditions, which in turn results in a decreased number of potential metallic nickel (Ni 0 ) sites available for hydrocarbon steam reforming. An increase in nickel crystallite size with time-on-stream was also observed using XRD, indicating that sintering may also play a role in loss of catalyst activity, although this is not considered the primary deactivation mechanism because activity loss was observed even when nickel crystallite sizes remained nearly constant.

Sulfur Tolerant Magnesium Nickel Silicate Catalyst for Reforming of Biomass Gasification Products to Syngas

“…The color of the MNS-washcoated monolith is light green (Figure 5b), similar to the catalyst color. The monolith was tested for reforming of oak wood gasification products [40] under the conditions of 900 °C, 14.4% H 2 , 10.4% CO, 9.8% CO 2 , 5.8% CH 4 , 13.2% N 2 , 44.6% H 2 O, 1.6% C 2 H 6 and C 2 H 4 , 0.2% C 3 H 8 and C 3 H 6 , 30 ppm naphthalene (when used), 22 ppm H 2 S and GHSV = 10,000 h −1 . H 2 S, naphthalene, C 2 and C 3 hydrocarbons were added to the feed for this testing.…”

Transformation of Sulfur Species during Steam/Air Regeneration on a Ni Biomass Conditioning Catalyst

“…1 It was observed that the catalyst deactivated with increasing cycle number, as shown by the decrease in maximum CH 4 conversion during each of the ten reaction cycles displayed in Table 2. This loss of activity coincided with the decrease in the amount of reducible Ni as indicated by TPR (Table 2), which we have previously reported and may be correlated to the formation of an irreducible NiAl 2 O 4 species.…”

“…Conversion of other species, such as benzene and tars, has been reported elsewhere and is not shown here because it is not a good indicator of activity due to high initial conversion levels that were observed. 1 Figure 1 also indicates where catalyst samples were obtained for sulfur XANES analysis (fresh, postreaction, regenerated, and reduced).…”

Techno-economic assessment of biomass-to-ethanol by indirect fluidized bed gasification: Impact of reforming technologies and comparison with entrained flow gasification

“…This concept was chosen in past works aimed at techno-economic assessments of thermochemical ethanol production [1][2][3][4][5][6]11]. The assumed conversion of tars and light hydrocarbons has been achieved using a nickelbased catalyst regenerated with mixtures of hydrogen/steam but a reduced catalyst lifetime due to poisoning is still unresolved [25,26].…”