Temperature dependence of the heterogeneous uptake of acrylic acid on Arizona test dust

In this study, the temperature dependence of the heterogeneous uptake of acrylic acid on Arizona test dust(ATD) has been investigated within a temperature range of 255–315 K using a Knudsen cell reactor. Combined with diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS) experiment, it was found that acrylic acid could adsorb on ATD via surface OH groups and convert to carboxylate on the particle surface. The kinetics study suggests that the initial true uptake coefficient(γt) of acrylic acid on ATD decreases from(4.02 ± 0.12) × 10~(-5) to(1.73 ± 0.05) × 10~/(-5)with a temperature increase from 255 to315 K. According to the temperature dependence of uptake coefficients, the enthalpy(ΔH obs)and entropy(ΔS obs) of uptake processes were determined to be-(9.60 ± 0.38) KJ/mol and-(121.55 ± 1.33) J·K/mol, respectively. The activation energy for desorption(E des) was calculated to be(14.57 ± 0.60) KJ/mol. These results indicated that the heterogeneous uptake of acrylic acid on ATD surface was sensitive to temperature. The heterogeneous uptake on ATD could affect the concentration of acrylic acid in the atmosphere, especially at low temperature.     

Recent progress on synthesis of ZIF-67-based materials and their application to heterogeneous catalysis

In recent years, an increasing amount of interest has been dedicated to the synthesis and application of ZIF-67-based materials due to their exceptionally high surface area, tunable porosity, and excellent thermal and chemical stabilities. This review summarizes the latest strategies of synthesizing ZIF-67-based materials by exploring the prominent examples. Then, the recent progress in the applications of ZIF-67-based materials in heterogeneous catalysis, including catalysis of the redox reactions, addition reactions, esterification reactions, Knoevenagel con-densations, and hydrogenation–dehydrogenation reactions, has been elaborately discussed. Finally, we end this work by shedding some light on the large-scale industrial production of ZIF-67-based materials and their applications in the future.     

Heterogeneous reaction of SO2 on CaCO3 particles: Different impacts of NO2 and acetic acid on the sulfite and sulfate formation

Despite the heterogeneous reaction of sulfur dioxide (SO₂) on mineral dust particles significantly affects the atmospheric environment, the effect of acidic gases on the formation of sulfite and sulfate from this reaction is not particularly clear. In this work, using the in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) technique, we employed a mineral dust particle model (CaCO₃) combined with NO₂ and acetic acid to investigate their effects on the heterogeneous reaction of SO₂ on CaCO₃ particles. It was found that water vapor can promote the formation of sulfite and simulated radiation can facilitate the oxidation of sulfite to sulfate. The addition of NO₂ or acetic acid to the reaction system altered the production of sulfate and sulfite accordingly. There was a synergistic effect between NO₂ and SO₂ that promoted the oxidation of sulfite to sulfate, and a competitive effect between acetic acid and SO₂ that inhibited the formation of sulfite. Moreover, light and water vapor can also affect the heterogeneous reaction of SO₂ with the coexistence of multiple gases. These findings improve our understanding of the effects of organic and inorganic gases and environmental factors on the formation of sulfite and sulfate in heterogeneous reactions.     

Fenton-like degradation of Methylene Blue using paper mill sludge-derived magnetically separable heterogeneous catalyst: Characterization and mechanism

For the paper industry, the disposal and management of the yielded sludge are a considerable challenge. In our work, the paper mill sludge-derived magnetically separable heterogeneous catalyst (PMS-Fe-380) was prepared easily through a facile synthesis method. The morphology and structure of PMS-Fe-380 were fully characterized by means of X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and Brunauer–Emmet–Teller analysis. The catalytic activity of PMS-Fe-380 was evaluated by degradation of Methylene Blue (MB). The reusability and stability of PMS-Fe-380 were evaluated in five repeated runs, which suggested that PMS-Fe-380 manifested excellent stability of catalytic activity. Moreover, leaching tests indicated that the leached iron is negligible (< 0.5 mg/L). This study provides an alternative environmentally friendly reuse method for paper mill sludge and a novel catalyst PMS-Fe-380 that can be considered as a promising heterogeneous Fenton-like catalyst.     

Directing technical change from fossil-fuel to renewable energy innovation: An application using firm-level patent data

In this paper we provide an analysis of directed technical change in the sector of electricity generation. We rely on patent data in fossil-fuel (FF) and renewable energy (REN) technologies for 5471 European firms over the 1978–2006 period. The novelty of our approach is in the focus on firm׳s heterogeneity in driving technological change. We make a distinction between small specialized firms, which innovate in only one type of technology, and large mixed firms, which innovate in both technologies, to analyse how REN patents can replace FF ones at the sector level both through a shift in innovation activities within existing firms and through firms׳ entry and exit. We use zero-inflated count data estimation techniques to identify the factors that affect specialized versus mixed firms׳ patenting behaviour both at the intensive (i.e., levels of innovation) and extensive (i.e., technological entry) margins. We further investigate the implications of our firm-level estimations for reducing the gap between REN and FF innovation at the aggregate level. We establish two key findings: (1) a decrease in the FF-REN technology gap mainly comes about through technological entry of specialized REN firms following an increase in REN market size; (2) increases in FF prices, FF market size, and FF knowledge stocks all increase the technology gap by increasing mixed firms FF innovation rates. An important implication of our results is that policies aimed at increasing REN innovation should focus on helping small firms to start and sustain innovation in the long-run.     

Do aerosols act as catalysts in the OH radical initiated atmospheric oxidation of volatile organic compounds?

Smog chamber/FTIR techniques were used to study the relative reactivity of OH radicals with methanol, ethanol, phenol, C₂H₄, C₂H₂, and p-xylene in 750 Torr of air diluent at 296±2 K. Experiments were performed with, and without, 500–8000 μg m⁻³ (4000–50 000 μm² cm⁻³ surface area per volume) of NaCl, (NH₄)₂SO₄ or NH₄NO₃ aerosol. In contrast to the recent findings of Oh and Andino (Atmospheric Environment 34 (2000) 2901, 36 (2002) 149; International Journal of Chemical Kinetics 33 (2001) 422) there was no discernable effect of aerosol on the rate of loss of the organic compounds via reaction with OH radicals. Gas kinetic theory arguments cast doubt upon the findings of Oh and Andino. The available data suggest that the answer to the title question is “No”. As part of this work the rate constants for reactions of OH radicals with methanol, ethanol, and phenol in 750 Torr of air at 296 K were determined to be: k_OH+CH3OH=(8.12±0.54)×10⁻¹³, k_OH+C2H5OH=(3.47±0.32)×10⁻¹² and k_OH+phenol=(3.27±0.31)×10⁻¹¹ cm³ molecule⁻¹ s⁻¹.     

Attenuation of a point blast shock wave in the dusty air

The behavior of the blast impulse initiated by a point blast in the dusty air is investigated theoretically. It is shown that the jumps of parameters at the shock front in the dusty air follow other regularities in comparison with the case of an ideal gas, beginning from the distance of three dynamic radii, so at ten dynamic radii the difference in overpressure exceeds 60%. When the air heterogeneity is taken into account, substantial gradual changes of wave profile come over and the total blast wave impulse can't be determined by the front overpressure only. The known far asymptotic law takes no place in the point blast flow at the volume dust densities ρ₂₀ > 3·10^?3 kg/m³. In contrast to the ideal gas, the shock front discontinuity vanishes in the dusty air at a finite distance from its origin and the blast wave eventually turns into a dispersive wave without discontinuity. The wave structure changing is studied in the process of the shock wave transformation into the dispersive wave.     

Analysis of the experimental results of the initiation of detonation in short tubes with kerosene–oxidizer mixtures

The paper describes the experimental investigation of detonation initiation in a mixture of kerosene–oxidant in a short test tube. Various mixtures of oxygen and nitrogen were used as an oxidant, from pure oxygen to the composition of air. The goal of the study was to determine the minimum diameter of the tube and the minimum level of energy needed for the direct initiation of detonation. As a result of the measurements the pressure courses were obtained for two kinds of cases: with and without (only shock waves) of fuel injection. The results of both kinds of measurements were compared, providing information about the initiation of detonation in a fuel–oxidizer mixture. Brief analyses of the results for different initiators and different oxidizers were performed and compared with the shock wave and Chapman–Jouget velocity.     

[Cu—γ—Al2O3]催化剂处理染料废水工艺条件研究

采用「Ｃｕ－γ－Ａｌ２Ｏ３」催化剂对由活性艳红Ｘ－３Ｂ配制的ＣＯＤｃｒ为５７００ｍｇ／Ｌ色度３１００倍的实际染料废水进行了催化氧化试验，试验表明，在控制ｐＨ＝４－５，Ｈ２Ｏ２用量为５．０ｍｇ／Ｌ，催化剂用量为３．０ｇ／Ｌ，ｔ＝７０℃和反应时间为２ｈ条件下，可获得ＣＯＤｃｒ去除率为７７％－７８％，脱色率为９９％的良好效果，且催化剂可再生使用。