热成像技术在乙醛生产设备热故障识别中的应用

通过红外热像的测试,结合设备结构特点．对已醛装置中的再生器、反应器、除沫器村里的脱落、裂纹及减薄等故障的热特性进行了分析与识别,获得的热像特性可供同类设备参考。     

乙醛装置废水循环利用

对乙醛装置洗涤塔单元和废水系统进行技术改造，装置部分废水循环利用，代替脱盐水作为洗涤塔的洗涤水，节能降耗，降低成本。     

Understanding the electrocatalytic activity of PtxSny in direct ethanol fuel cells

In the present work, the activity of Pt_xSn_y/C catalysts towards ethanol, acetaldehyde and acetic acid electrooxidation reactions is investigated for each one separately by means of cyclic voltammetry. To this purpose, a series of Pt_xSn_y/C catalysts with different atomic ratio (x:y = 2:1, 3:2, 1:1) and small particle size (∼3 nm) are fast synthesized by using the pulse microwave assisted polyol method. The catalysts are well dispersed over the carbon support based on the physicochemical characterization by means of XRD and TEM. Concerning the ethanol electrooxidation, it is found that the Sn addition strongly enhances Pt's electrocatalytic activity and the contributing effect of Sn depends on: (i) the Sn content and (ii) the operating temperature. More precisely, at lower temperatures, Sn-rich catalysts exhibit better ethanol electrooxidation performance while at higher temperatures Sn-poor catalysts give better performance. In the case of acetaldehyde electrooxidation, Pt₁Sn₁/C catalyst exhibits the highest activity at all the investigated temperatures; due to the role of Sn, which could effectively remove C₂ species and inhibit the poison formation by supplying oxygen-containing species. Finally, it is found that the Pt_xSn_y/C catalysts are almost inactive (little current was measured) towards the acetic acid electrooxidation. The above findings indicate that Sn cannot substantially promote the electrooxidation of acetic acid to C₁ species.     

Removal of unpleasant odor gases using an Ag-Mn catalyst

Conversions of acetaldehyde and trimethylamine as model unpleasant odor gases were measured over several catalysts. The activities of Ag and Mn₂O₃ were the highest of the catalysts that consisted of a single component. The addition of Ag to manganese oxide enhanced the activity and the durability of the catalysts. The activity of Mn catalyst was improved by the addition of Ag up to 40 atom-%, and the maximum activity was observed at 10 atom-%. Acetaldehyde was considered to be decomposed over the AgMn catalyst by oxidation according to the measurement of reaction products. The oxidation state of silver was maintained on the surface of the AgMn catalyst calcined at 773 K. The amount of oxygen adsorbed on the surface of the AgMn catalyst was about 2.9 times as much as that on Mn₂O₃. These experimental data suggested that manganese oxide supplied oxygen to silver and that the oxidation state of silver was maintained on the surface of the AgMn catalyst.     

Reactivity of acetaldehyde at platinum and rhodium in acidic media. A DEMS study

The electrochemical behaviour of acetaldehyde at platinum and rhodium electrodes in acid solutions was studied applying differential electrochemical mass spectrometry (DEMS). In an acetaldehyde-containing solution, CO₂ was the sole electrooxidation product detected at both electrodes, whereas only methane was recorded in the hydrogen region. The production of acetic acid was indirectly established at platinum from DEMS. Residues were studied through the design of flow cell experiments. As for the acetaldehyde-containing solution, the adsorbates produce CO₂ and methane during the oxidation and reduction processes, respectively. However, ethane was also observed at platinum during the cathodic stripping of the adspecies. The yield of these substances depends on the adsorption potential (E_ad). These results suggest that the fragmentation of acetaldehyde occurs during adsorption and reduction reactions, and the extent of the CC bond scission is influenced by the E_ad and the nature of the electrode, being favoured at rhodium.     

Vapor phase reactions of acetaldehyde over type X zeolites

Vapor phase reactions of acetaldehyde over X zeolites were studied at 1 atm and 300–400°C using a fixed-bed, integral-flow reactor. The catalytic activities decreased in the order: KX > NaX > HX, in accordance with the trend of catalyst basic strength. The product selectivities of 3-hydroxybutanal, butanal and benzene increased with increasing catalyst basic strength, whereas the reverse trend was found for those of ethylene oxide, propane and dihydrofurans. The reaction network and associated mechanisms are proposed and discussed. The main pathway was self-condensation of acetaldehyde to 3-hydroxybutanal, followed by dehydration to 2-butenal. Other side reactions include isomerization, reduction, cyclodehydration and sequential cross-condensation–cyclodehydration. The kinetic parameters for acetaldehyde reactions over NaX zeolite were estimated.     

Electrocatalytic oxidation of acetaldehyde on Pt alloy electrodes

Reaction intermediates occurring during the oxidation of acetaldehyde were investigated by in situ infrared reflectance spectroscopy (SPAIRS and SNIFTIRS techniques). These measurements, showing that acetaldehyde was transformed into CO and CO₂ successively, allowed us to choose a suitable potential program to oxidize electrocatalytically the reactant on binary and ternary platinum alloy electrodes with two compositions (Pt/Os and Pt/Ru/Os). IR results were useful to set a potential pulse program which allowed to adsorb dissociatively the organic compound. The analysis of the electrolysis products was performed by high performance liquid chromatography (HPLC). Acetic acid, formic acid and carbon dioxide were determined as the main oxidation products of acetaldehyde.     

Effect of total milk solid content adjusted by adding ultrafiltered milk retentate on quality of set mango yoghurt

The quality of set mango yoghurt prepared by varying total milk solids (TMS) level in mango yoghurt mix, by adding 5× ultrafiltered cow skim milk retentate and cow milk cream, was investigated. The water‐holding capacity (WHC) and values of textural attributes of mango yoghurt increased, whereas body and texture and overall acceptability scores decreased significantly (P < 0.05) with increasing TMS level. The optimised product (10.2% TMS level) was compared with conventional mango yoghurt. Acetaldehyde concentration, WHC, values of textural attributes, body and texture, overall acceptability scores and pH were significantly (P < 0.05) higher in optimised compared with conventional mango yoghurt.     

Co-application of liquid phase plasma process for hydrogen production and degradation of acetaldehyde over NiTiO2 supported on porous materials

Photocatalytic decomposition of acetaldehyde-contained wastewater was assessed for the degradation of pollutants and the production of hydrogen. Liquid phase plasma was applied in the photoreaction as a light source. The evolution of hydrogen and acetaldehyde degradation were characterized by the photocatalytic decomposition system. Ni-loaded TiO₂ photocatalysts and various porous materials were introduced to the photocatalytic reaction. The photochemical decomposition by irradiation of the liquid phase plasma without photocatalysts produced some hydrogen evolution with the degradation of acetaldehyde, which was attributed to the decomposition of the reactant by active species generated by the irradiation of liquid phase plasma. The Ni loading on TiO₂ brought out an enhancement of acetaldehyde degradation and hydrogen evolution. In the photocatalysis of acetaldehyde-contained wastewater using the liquid phase plasma, hydrogen evolution was accelerated due to the additional hydrogen production by the photocatalytic decomposition of acetaldehyde. The porous materials could be used as an effective photocatalytic support. MCM-41 mesoporous material has acted as a highly efficient photocatalytic support to the TiO₂ photocatalyst.     

浅谈降低微型啤酒中乙醛含量的措施

本文针对微型啤酒中乙醛含量高引进啤酒上头的因素进行探讨,论述了啤酒生产过程中乙醛的生产及影响啤酒中乙醛含量的因素,并提出了如何通过合理的生产工艺进行控制,以保证啤酒的质量。