Abstract
ZSM-5 zeolite coating supported on SiC foams was prepared by a precursor dispersion-secondary growth method and the resulting structured ZSM-5/SiC foam catalyst was used for the proof-of-concept study of catalytic bio-oils upgrading (i.e. deoxygenation of the model compounds of methanol and anisole) in reference to ZSM-5 catalyst pellets. A layer of ZSM-5 coating with inter-crystal porosity on SiC foams was produced by curing the zeolite precursor thermally at 80 °C. The use of SiC foam as the zeolite support significantly improved transport phenomena compared to the packed-bed using ZSM-5 pellets, explaining the comparatively good catalytic performance achieved by the structured ZSM-5/SiC foam catalyst. In comparison with the ZSM-5 pellets, the ZSM-5/SiC foam catalyst showed 100.0% methanol conversion (at the weight hourly space velocity, WHSV, of 8 h–1) and 100.0% anisole conversion (at WHSV =5 h−1) at the initial stage of the processes, while only about 3% were obtained for the ZSM-5 pellets, under the same conditions. Based on the comparative analysis of the characterisation data on the fresh and spent catalysts, the deactivation mechanisms of the ZSM-5/SiC and the ZSM-5 pellet catalysts were explained. The process intensification using SiC foam to support ZSM-5 improved the global gas-to-solid mass transfer notably, and hence mitigating the pore blocking due to the carbon deposition on the external surface of supported ZSM-5.
Highlights
Bio-oils from the fast pyrolysis of biomass have the potential to be converted into fuels and chemicals, addressing the issues associated with the usage and shortage of fossil fuels [1], especially environmental ones such as airborne particulates, carbon dioxide (CO2), sulphur oxides (SOx) and nitrogen oxides (NOx)
X-ray diffraction (XRD) (Fig. 1) and scanning electron microscopy (SEM) results (Fig. 2a) show that the amorphous precursor gel was obtained after three-hour synthesis, whereas silicalite-1 seeds were formed by extending the synthesis time to eight hours (Figs. 1 and 2c), which is consistent with the results for the previous study [42]
Based on the developed dispersion-based method, we presented the results of the ZSM-5 coating morphology on silicon carbide (SiC) foams by means of varying the zeolite precursor heat treatment temperature
Summary
Bio-oils from the fast pyrolysis of biomass have the potential to be converted into fuels and chemicals, addressing the issues associated with the usage and shortage of fossil fuels [1], especially environmental ones such as airborne particulates, carbon dioxide (CO2), sulphur oxides (SOx) and nitrogen oxides (NOx). Structured open-cell foams, especially silicon carbide (SiC) foams, are good catalyst supports for process intensification due to their intrinsic (e.g. high thermal conductivity of SiC [30]) and structural properties (e.g. high open porosity and irregular pore structure [32,33,34]) These intrinsic pore structures generally promote the global mass transfer across the foam beds [26,32,33]. The seed-facilitated secondary growth method can promote the selective growth of zeolites on foam supports [34,37], the resulting dense coating with intergrown zeolite crystals may impose additional mass transfer resistance during application due to the low porosity and accessibility. A combination of nitrogen (N2) physisorption, ammonia temperature-programmed desorption (NH3-TPD) and thermogravimetric analysis (TGA) was used to compare and contrast the ZSM-5/SiC foam catalyst and ZSM-5 catalyst pellets (as-prepared and used ones) regarding their pore texture and acidity properties to understand their deactivation behaviours
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
