Filtration
failure occurs when filter media are blocked by accumulated
solid particles. Suitable operating conditions were investigated for
cake cleaning by partial oxidation of filter-cake particles (FCPs)
during biomass gasification. The mechanism of the FCP partial oxidation
was investigated in a ceramic filter and by using thermogravimetric
analysis through a temperature-programmed route in a 2 vol % O2–N2 environment. Partial oxidation of the
FCPs in the simulated product gas environment was examined at 300–600
°C in a ceramic filter that was set and heated in a laboratory-scale
fixed reactor. Four reaction stages, namely, drying, preoxidation,
complex oxidation, and nonoxidation, occurred in the FCP partial oxidation
when the temperature increased from 30 to 800 °C in a 2 vol %
O2–N2 environment. Partial oxidation
was more effective for FCP mass loss from 275 to 725 °C. Experimental
results obtained in a ceramic filter indicated that the best operating
temperature and FCP loading occurred at 400 °C and 1.59 g/cm2, respectively. The FCPs were characterized before and after
partial oxidation by Fourier-transform infrared spectroscopy, scanning
electron microscopy, and Brunaeur–Emmett–Teller analysis.
Fourier-transform infrared spectroscopy analysis revealed that partial
oxidation of the FCPs can result in a significant decrease in C–H
n
(alkyl and aromatic) groups and an increase
in CO (carboxylic acids) groups. The scanning electron microscopy
and Brunaeur–Emmett–Teller analyses suggest that, during
partial oxidation, the FCPs underwent pore or pit formation, expansion,
amalgamation, and destruction.
High-silica MFI zeolite membranes supported on porous α-alumina discs were prepared by a seeded secondary growth method, using tetrapropylammonium hydroxide (TPAOH) as organic template. First, nanocrystals were deposited on rough α-Al2O3 discs by a spin-on process. Then, based on controlling the H2O/ Si molar ratio of the synthetic solution, a restricting in-plane h0h-oriented growth method with an ultra-dilute precursor was designed to prepare non-defective zeolite membranes that were as thin as possible. Finally, crosslinked and dense MFI zeolite membranes were prepared after the third synthesis step, giving a membrane layer thickness of about 8 μm, including~5 μm dense layers and~3 μm intermediate layers. A novel, two-step method, coupling by low-temperature hydrocracking and oxidation, is proposed for efficient removal of the template from zeolite membranes. Compared with traditional high-temperature calcination, template removal by the two-step method could eliminate the grain boundary defects formed in response to stresses induced by heat treatment. As a result, the membranes treated by the two-step detemplation method displayed a preferable CO2/N2 separation factor (about 5.2) and high CO2 permeance (5.8 × 10-7 mol•m-2 •s-1 •Pa-1) at 30°C.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.