Catalytic Material with Enhanced Contacting Efficiency for Volatile Organic Compound Removal at Ultrashort Contact Time

Abstract

A unique catalyst structure, microfibrous entrapped catalyst (MFEC), was prepared by entrapping support particles (γ-Al2O3, 150–250 μm diam) into metal (Ni-200) microfibers and forming thin flexible sheets. Pleated structures of MFECs containing Pd/γ-Al2O3, Pd–Mn/γ-Al2O3, and Pd–Ce/γ-Al2O3 were investigated systematically for volatile organic compound (VOC) removal at various face velocities (ca. 3–30 m/s) and at low temperatures (<473 K). The optimized structure of MFEC (e.g., W-structure with 8 μm Ni fiber) resulted intralayer residence times from 750 to 65 μs with pressure drops from 0.35 to 10.22 kPa. The study exhibited that low intralayer residence times had a significant effect on the catalytic reaction which followed the Mars–Van Krevelen mechanism in this velocity controlled region. The overall reaction rate for VOC removal was limited by the surface reaction. Furthermore, mixed metal oxide based MFECs showed better performance in VOC removal due to the high oxygen storage capacity of reducible oxides. The performance of pleated MFEC was calculated in terms of heterogeneous contacting efficiency (ηHCE), which relies on the logarithmic removal of reactant concentrations per unit of the pressure drop.

Recent Development of Catalysts for Removal of Volatile Organic Compounds in Flue Gas by Combustion: A Review

“…The Pd based catalyst operates at a slightly higher range of temperature between 200 and 300 ∘ C as compared to Pt [31][32][33][34]. The oxidation state of Pd influences its catalytic activity and Dégé et al reported that Pd 0 is the active phase and its catalytic performance is highly dependent on its load on supports [31,32].…”

Comparison of wash‐coated monoliths vs. microfibrous entrapped catalyst structures for catalytic VOC removal

“…Figure 3 shows the uniquely designed system for testing microfibrous material to achieve catalytic VOC removal at microsecond contact time. 14 The test setup consists of a high pressure 40 hp radial blower (Fan Equipment Company), which circulates air inside the closed-loop system. A variable speed drive is used to control the system speed, which can reach over 30 m/s inlet velocity.…”

“…However, this theoretical investigation required an experimental verification. Therefore, a performance evaluation parameter, heterogeneous contacting efficiency ( η HCE ), was applied to evaluate the performance of those aforementioned reactor geometries . Balakotaiah and West and Giani et al have also considered this parameter for comparing the performance of monolith with packed bed and catalytic foam.…”

“…Therefore, a performance evaluation parameter, heterogeneous contacting efficiency (g HCE ), was applied to evaluate the performance of those aforementioned reactor geometries. 14 Balakotaiah and West 16 and Giani et al 17 have also considered this parameter Correspondence concerning this article should be addressed to B. J. Tatarchuk at tatarbj@auburn.edu. V C 2014 American Institute of Chemical Engineers for comparing the performance of monolith with packed bed and catalytic foam.…”

“…The authors have mentioned the importance and the mechanistic details of VOC removal for high performance platforms, for example, military ships, tanks, aircraft cabin air, and so forth in their previous study. 14 Among the toxic air pollutants regulated by EPA, 90% belongs to VOCs. The authors had considered the aforementioned VOCs based on the survey conducted by Nagda and Rector.…”