Mesoporous molecular sieve-based materials for catalytic oxidation of VOC: A review.

As the main contributor of the formation of particulate matter as well as ozone, volatile organic compounds (VOCs) greatly affect human health and the environmental quality. Catalytic combustion/oxidation has been viewed as an efficient, economically feasible and environmentally friendly way for the elimination of VOCs. Supported metal catalyst is the preferred type of catalysts applied for VOCs catalytic combustion because of the synergy between active components and support as well as its flexibility in the composition. The presence of support not only plays the role of keeping the catalyst with good stability and mechanical strength, but also provides a large specific surface for the good dispersion of active components, which could effectively improve the performance of catalyst as well as decrease the usage of active components, especially the noble metal amount. Mesoporous molecular sieves, owing to their large surface area, unique porous structures, large pore size as well as uniform pore-size distribution, were viewed as superior support for dispersing active components. This review focuses on the recent development of mesoporous molecular sieve supported metal catalysts and their application in catalytic oxidation of VOCs. The effect of active component types, support structure, preparation method, precursors, etc. on the valence state, dispersion as well as the loading of active species were also discussed and summarized. Moreover, the corresponding conversion route of VOCs was also addressed. This review aims to provide some enlightment for designing the supported metal catalysts with superior activity and stability for VOCs removal.

Untested assumptions perpetuate stereotyping: Learning in the absence of evidence.

In the present work, we set out to assess whether and how much people learn in response to their stereotypic assumptions being confirmed, being disconfirmed, or remaining untested. In Study 1, participants made a series of judgments that could be influenced by stereotypes and received feedback that confirmed stereotypes the majority of the time, feedback that disconfirmed stereotypes the majority of the time, or no feedback on their judgments. Replicating past work on confirmation bias, patterns in the conditions with feedback indicated that pieces of stereotype-confirming evidence exerted more influence than stereotype-disconfirming evidence. Participants in the Stereotype-Confirming condition stereotyped more over time, but rates of stereotyping for participants in the Stereotype-Disconfirming condition remained unchanged. Participants who received no feedback, and thus no evidence, stereotyped more over time, indicating that, matching our core hypothesis, they learned from their own untested assumptions. Study 2 provided a direct replication of Study 1. In Study 3, we extended our assessment to memory. Participants made judgments and received a mix of confirmatory, disconfirmatory, and no feedback and were subsequently asked to remember the feedback they received on each trial, if any. Memory tests for the no feedback trials revealed that participants often misremembered that their untested assumptions were confirmed. Supplementing null hypothesis significance testing, Bayes Factor analyses indicated the data in Studies 1, 2, and 3 provided moderate-to-extreme evidence in favor of our hypotheses. Discussion focuses on the challenges these learning patterns create for efforts to reduce stereotyping.

Study of reaction mechanism based on further promotion of low temperature degradation of toluene using nano-CeO2/Co3O4 under microwave radiation for cleaner production in spraying processing.

Cleaner production in spraying processing was presented by advanced low temperature oxidation technology using combined methods of microwave radiation and nano-composites. Activities of samples for oxidation of toluene were estimated and the result exhibited that application of microwave radiation and nano-materials greatly promoted activities of catalysts. Moreover, the doping of Ce further enhanced catalytic activities. Samples of 5% Ce-Co showed optimal activity with conversion rate of 70% and CO2 selection of 96% at 120 ℃ and 210 ℃, respectively. The lowest Ea (33.45 kJ/mol) was obtained calculating from kinetics process under microwave radiation using 5% Ce-Co indicating that the degradation of toluene might proceed more readily. Microwave absorption properties were first used tentatively to study the effect of "hot spots" induced by microwave radiation on catalytic oxidation of VOCs. Further, physicochemical properties of samples were also showed by XRD, SEM and XPS profiles to study oxidation activities of toluene. The maximum difference of toluene oxidation between no water and in water using 5% Ce-Co at 210 ℃ was only 3.06% manifesting that effects of moisture on activities were weak under microwave radiation. A possible degradation track using microwave heating was presented by the analysis of reaction byproducts using the GC-MS.

Mn-CeOx/MeOx(Ti, Al)/cordierite preparation with ultrasound-assisted for non-methane hydrocarbon removal from cooking oil fumes.

Cooking oil fumes (COFs) which contains a variety of volatile organic compounds (VOCs) is noxious not only to the environment but also to human health. Among COFs, the Non-methane Hydrocarbon (NMHC) removal rate is an index of the removal rate of COFs in the latest COFs purification standard (DB 11/1488-2018). Ultrasonic treatment can assist the synthesis of catalysts by creating "cavitation", which can improve the surface microtopography of catalysts. The research results in this paper revealed that the NMHC conversion of catalysts with ultrasonic treatment increased significantly. Besides, the samples that coated TiO2 had a higher conversion of NMHC than that coated Al2O3 because TiO2 has better oxidation performance than Al2O3. According to the XPS, SEM, EDS and BET data, because of the enhancement of interaction of the active components of catalysts caused by ultrasonic intervention, T-UU-CTAB exhibited the best catalytic performance, which attributed to the high levels of Mn4+/Mn3+, Ce4+/Ce3+ and Oads/Olatt, more developed pore structure owing to the smaller particle size, higher dispersion of active components, larger specific surface area and larger total pore volume produced by the ultrasonic treatment. Moreover, the conversion of NMHC over T-UU-CTAB is 93.6% at 400 °C.