LOW-TEMPERATURE WATER-VAPOR CONVERSION OF ETHANOL ON THE Ni/ZnO CATALYST IN A MICROCHANNEL REACTOR

Recent studies have shown that appropriate levels of alkali promotion can significantly improve the rate of low-temperature water gas shift (LT-WGS) on a range of catalysts. At sufficient loadings, the alkali metal can weaken the formate C–H bond and promote formate dehydrogenation, which is the proposed rate determining step in the formate associative mechanism. In a continuation of these studies, the effect of Rb promotion on Pt/ZrO2 is examined herein. Pt/ZrO2 catalysts were prepared with several different Rb loadings and characterized using temperature programmed reduction mass spectrometry (TPR-MS), temperature programmed desorption (TPD), diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), an X-ray absorption near edge spectroscopy (XANES) difference procedure, extended X-ray absorption fine structure spectroscopy (EXAFS) fitting, TPR-EXAFS/XANES, and reactor testing. At loadings of 2.79% Rb or higher, a significant shift was seen in the formate ν(CH) band. The results showed that a Rb loading of 4.65%, significantly improves the rate of formate decomposition in the presence of steam via weakening the formate C–H bond. However, excessive rubidium loading led to the increase in stability of a second intermediate, carbonate and inhibited hydrogen transfer reactions on Pt through surface blocking and accelerated agglomeration during catalyst activation. Optimal catalytic performance was achieved with loadings in the range of 0.55–0.93% Rb, where the catalyst maintained high activity and exhibited higher stability in comparison with the unpromoted catalyst.

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Analysis of Mechanical Properties and Mechanism of Natural Rubber Waterstop after Aging in Low-Temperature Environment

Polymers ◽

10.3390/polym13132119 ◽

2021 ◽

Vol 13 (13) ◽

pp. 2119

Author(s):

Lin Yu ◽

Shiman Liu ◽

Weiwei Yang ◽

Mengying Liu

Keyword(s):

Mechanical Properties ◽

Low Temperature ◽

Energy Dispersive Spectrometry ◽

Permanent Deformation ◽

Test Chamber ◽

Accelerate Aging ◽

Aging Mechanism ◽

Temperature Environment ◽

Freezing Test ◽

Temperature Water

In order to elucidate the aging performance and aging mechanism of a rubber waterstop in low-temperature environments, the rubber waterstops were placed in the freezing test chamber to accelerate aging, and then we tested its tensile strength, elongation, tear strength, compression permanent deformation and hardness at different times. Additionally, the damaged specimens were tested by scanning electron microscope, Fourier transform infrared spectroscopy and energy dispersive spectrometry. The results showed that with the growth of aging time, the mechanical properties of the rubber waterstop are reduced. At the same time, many protrusions appeared on the surface of the rubber waterstop, the C element gradually decreased, and the O element gradually increased. During the period of 72–90 days, the content of the C element in the low-temperature air environment significantly decreased compared with that in low-temperature water, while the content of O element increased significantly.

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Rolling membrane powered by low-temperature steam as a new approach to generate mechanical energy

Scientific Reports ◽

10.1038/s41598-020-73732-7 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Chongshan Yin ◽

Qicheng Liu ◽

Qing Liu

Keyword(s):

Water Vapor ◽

Low Temperature ◽

Combustion Engine ◽

Mechanical Energy ◽

Heat Energy ◽

Steam Engine ◽

Low Grade ◽

Human Society ◽

New Approach ◽

Low Grade Heat

Abstract How to convert heat energy into other forms of usable energy more efficiently is always crucial for our human society. In traditional heat engines, such as the steam engine and the internal combustion engine, high-grade heat energy can be easily converted into mechanical energy, while a large amount of low-grade heat energy is usually wasted owing to its disadvantage in the temperature level. In this work, for the first time, the generation of mechanical energy from both high- and low-temperature steam is implemented by a hydrophilic polymer membrane. When exposed to water vapor with a temperature ranging from 50 to 100 °C, the membrane repeats rolling from one side to another. In nature, this continuously rolling of membrane is powered by the steam, like a miniaturized “steam engine”. The differential concentration of water vapor (steam) on the two sides of the membrane generates the asymmetric swelling, the curve, and the rolling of the membrane. In particular, results suggest that this membrane based “steam engine” can be powered by the steam with a relatively very low temperature of 50 °C, which indicates a new approach to make use of both the high- and low-temperature heat energy.

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