Tingyu Zhu

Bio: Tingyu Zhu is an academic researcher from Chinese Academy of Sciences. The author has contributed to research in topics: Catalysis & Flue gas. The author has an hindex of 19, co-authored 93 publications receiving 1090 citations.

Mercury removal from coal combustion flue gas by modified fly ash

Abstract: Fly ash is a potential alternative to activated carbon for mercury adsorption. The effects of physicochemical properties on the mercury adsorption performance of three fly ash samples were investigated. X-ray fluorescence spectroscopy, X-ray photoelectron spectroscopy, and other methods were used to characterize the samples. Results indicate that mercury adsorption on fly ash is primarily physisorption and chemisorption. High specific surface areas and small pore diameters are beneficial to efficient mercury removal. Incompletely burned carbon is also an important factor for the improvement of mercury removal efficiency, in particular. The C M bond, which is formed by the reaction of C and Ti, Si and other elements, may improve mercury oxidation. The samples modified with CuBr2, CuCl2 and FeCl3 showed excellent performance for Hg removal, because the chlorine in metal chlorides acts as an oxidant that promotes the conversion of elemental mercury (Hg-0) into its oxidized form (Hg2+). Cu2+ and Fe3+ can also promote Hg-0 oxidation as catalysts. HCl and O-2 promote the adsorption of Hg by modified fly ash, whereas SO2 inhibits the Hg adsorption because of competitive adsorption for active sites. Fly ash samples modified with CuBr2, CuCl2 and FeCl3 are therefore promising materials for controlling mercury emissions.

Haze insights and mitigation in China: an overview.

Abstract: The present article provides an overview of the chemical and physical features of haze in China, focusing on the relationship between haze and atmospheric fine particles, and the formation mechanism of haze. It also summarizes several of control technologies and strategies to mitigate the occurrence of haze. The development of instruments and the analysis of measurements of ambient particles and precursor concentrations have provided important information about haze formation. Indeed, the use of new instruments has greatly facilitated current haze research in China. Examples of insightful results include the relationship between fine particles and haze, the chemical compositions and sources of particles, the impacts of the aging process on haze formation, and the application of technologies that control the formation of haze. Based on these results, two relevant issues need to be addressed: understanding the relationship between haze and fine particles and understanding how to control PM2.5.

Remarkable N2-selectivity enhancement of practical NH3-SCR over Co0.5Mn1Fe0.25Al0.75Ox-LDO: The role of Co investigated by transient kinetic and DFT mechanistic studies

Abstract: A Co0.5Mn1Fe0.25Al0.75Ox-LDO catalyst was developed which showed excellent performance for the low-temperature NH3-SCR. NOx conversions ∼100% were achieved in the whole 100-250 °C range, while after 10-h operation at 150 °C with 100 ppm SO2/5 vol% H2O in the feed, the NOx conversion was maintained at 80%. This catalyst provided a much better N2-selectivity than the Mn1Fe0.25Al0.75Ox-LDO and Mn1Al1Ox-LDO, especially at 150-300 °C. It was found that Co0.5Mn1Fe0.25Al0.75Ox possessed higher surface acidity and reducibility, while XPS analyses indicated an electron transfer between Co3+/Co2+ and Mn4+/Mn3+ redox cycles, leading to a much lower N2O formation, supported by Density Functional Theory (DFT) calculations. Detailed analysis of gas responses obtained upon various step-gas switches was performed, which allowed to measure the surface concentration and reactivity of preadsorbed NOx-s and NHx-s leading to N2 and N2O. Transient kinetic and DFT studies strongly suggested likely mechanisms of NH3-SCR and the critical role of Co for N2-selectivity enhancement.

Promotional effect of Ce doping in Cu4Al1Ox – LDO catalyst for low-T practical NH3-SCR: Steady-state and transient kinetics studies

Abstract: There are very few catalysts reported so far to withstand poisoning by the co-presence of SO2, HCl and H2O in the flue gas stream for the NH3-SCR. The purpose of this work was to report for the first time, to the best of our knowledge, the development of a new catalyst, Ce-2/Cu4Al1Ox-layered double oxide (LDO) with high low-temperature de-NOx activity and high poisoning resistance in the presence of H2O, HCl and SO2 in the feed gas stream. In particular, Ce-2/ Cu4Al1Ox-LDO catalyst in the presence of 5% H2O, 100 ppm HCl and 100 ppm SO2 in the NH3-SCR feed gas stream presented after 9 h of continuous reaction at 200 degrees C a relatively stable NOx conversion (ca. 57.2%), where all other three control catalysts tested, namely: Cu/Al2O3,Cu-Ce/Al2O3 and Cu-4 Al3Ox showed severe deactivation, where NOx conversion values of similar to 0, 0 and 51%, respectively, were measured. It should be noted that the Ce-2/Cu(4)Al(1)O(x)catalyst achieved NOx conversion of 95.3% at 200 degrees C in the absence of HCI and SO2 in the feed gas stream. A suit of experimental techniques such as BET, XPS, ICS, in situ DRIFTS, pyridine- and NH3-FTIR, NH3-TPD, H-2-TPR and transient NH3 chemisorption and NH3-SCR kinetics were employed to reveal possible reasons for the high activity and poisoning resistance exhibited by the Ce-2/Cu4Al1Ox catalytic system. XRD and XPS analyses showed that Ce-2/Cu-4 Al1Ox had highly dispersed Cu2+ and Ce3+ species, which likely promote the rate of NH3-SCR. Py-FTIR, NH3-TPD and H-2-TPR results indicated that Ce-2/Cu-4 Al1Ox has a larger concentration of surface acid sites and stronger redox properties. According to H-2-TPR, ICS and insitu DRIFTS analyses, the redox properties of Ce-2/Cu-4 Al1Ox were significantly less affected by the presence of HCI and SO2 gases, and lower amounts of metal sulfate and metal chloride species were formed, thus proving its exhibited poisoning resistance. Transient kinetics experiments revealed that the larger site reactivity (k, s( -1)) and NO oxidation rate to NO2 and not the surface coverage of adsorbed NHx-s active intermediates dictates the higher rate of NH3-SCR over Ce-2/Cu-4 Al1Ox compared to Cu/Al2O3 and Cu-Ce/Al2O3 non LDO- materials.

Recent Advances in the Catalytic Oxidation of Volatile Organic Compounds: A Review Based on Pollutant Sorts and Sources.

Abstract: It is well known that urbanization and industrialization have resulted in the rapidly increasing emissions of volatile organic compounds (VOCs), which are a major contributor to the formation of secondary pollutants (e.g., tropospheric ozone, PAN (peroxyacetyl nitrate), and secondary organic aerosols) and photochemical smog. The emission of these pollutants has led to a large decline in air quality in numerous regions around the world, which has ultimately led to concerns regarding their impact on human health and general well-being. Catalytic oxidation is regarded as one of the most promising strategies for VOC removal from industrial waste streams. This Review systematically documents the progresses and developments made in the understanding and design of heterogeneous catalysts for VOC oxidation over the past two decades. It addresses in detail how catalytic performance is often drastically affected by the pollutant sources and reaction conditions. It also highlights the primary routes for catalyst deactivation and discusses protocols for their subsequent reactivation. Kinetic models and proposed oxidation mechanisms for representative VOCs are also provided. Typical catalytic reactors and oxidizers for industrial VOC destruction are further discussed. We believe that this Review will provide a great foundation and reference point for future design and development in this field.

Secondary Organic Aerosol Formation from Anthropogenic Air Pollution: Rapid and Higher than Expected

Abstract: [1] The atmospheric chemistry of volatile organic compounds (VOCs) in urban areas results in the formation of ‘photochemical smog’, including secondary organic aerosol (SOA). State-of-the-art SOA models parameterize the results of simulation chamber experiments that bracket the conditions found in the polluted urban atmosphere. Here we show that in the real urban atmosphere reactive anthropogenic VOCs (AVOCs) produce much larger amounts of SOA than these models predict, even shortly after sunrise. Contrary to current belief, a significant fraction of the excess SOA is formed from first-generation AVOC oxidation products. Global models deem AVOCs a very minor contributor to SOA compared to biogenic VOCs (BVOCs). If our results are extrapolated to other urban areas, AVOCs could be responsible for additional 3–25 Tg yr−1 SOA production globally, and cause up to −0.1 W m−2 additional top-of-the-atmosphere radiative cooling.