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Preparation, characterization, and thermal decomposition catalytic activity of novel combustion rate catalysts

100%

Yao Y. , Hu S.

tom Vol. 42, No. 3

160--170

The study successfully synthesized a combustion catalyst consisting of copper atoms anchored onto a carbon black support. The 2,4,6,8,10,12-hexanitrohexaazaisowurtzitane (CL-20), 1,1-diamino-2,2-dinitroethylene (FOX-7), cyclotetramethylene-tetranitramine, and ammonium perchlorate energetic materials were studied and analyzed using high-temperature pyrolysis process and catalytic oxidation thermal decomposition kinetics analysis. The research results indicate that the addition of the catalyst CB@Cu significantly reduces the activation energy during the pyrolysis process of energetic materials, leading to an earlier decomposition temperature and a significant catalytic effect. After adding catalyst CB@Cu, the endothermic peaks of the three energetic materials shifted toward lower temperatures, but the magnitude of the movement was relatively small. The maximum thermal decomposition temperature has been reduced by 3–5°C compared to that before the addition of the catalyst. At lower temperatures, the catalyst has a better catalytic effect on the energetic materials. The catalyst indicates the formation of electron transfer and the presence of metal Cu ligands, increasing the number of active sites with energetic materials, making the heat release of energetic materials more concentrated and increasing the degree of thermal decomposition.

Badanie regeneracji katalizatorów MoO3/Al2O3 i MoO3/Al2O3 - Sn(CH3)4 aktywnych w metatezie olefin

100%

Handziuk J. , Ogonowski J.

tom T. 82, nr 4

282-285

Performance studies of premixed blended hydraulic cement to revolutionize concrete production

100%

Lin K.-L. , Lin W.-T. , Fiala L. , Kočí J. , Lee P.-E. , Hsu H.-M.

tom Vol. 42, No. 3

139--159

In recent years, ready-mix concrete plants have increasingly utilized premixed blended hydraulic cement. These formulations incorporate a higher mineral admixture content than traditional ternary concrete mixtures, resulting in improved durability, compactness, and reduced hydration heat during curing. This study examined four concrete proportions with a water–binder ratio of 0.32, focusing on workability, compression strength, and chloride penetration resistance. The research also considered economic effects and carbon emissions. The findings revealed that premixed blended hydraulic cement improved late strength development and reduced chloride permeability. Additionally, the partial replacement of cement with silica fume enhanced early strength and chloride resistance. However, these benefits came with trade-offs, including adverse effects on workability and increased hydration heat. Notably, a 50% cement mixture in premixed blended hydraulic cement emitted 42–49% less CO2 than conventional formulations, highlighting its potential for reducing environmental impact in concrete production.

Badania aktywności bimetalicznych katalizatorów Pd-Ag/Al2O3 do utleniania metanu

75%

Krzaczek P. , Maj G. , Piekarski W. , Nazimek D.

2016

tom T. 95, nr 11

2200--2205

Przedstawiono wyniki badań fizykochemicznych właściwości stopowych katalizatorów Pd-Ag/Al2 O3 przeznaczonych do utleniania metanu do metanolu w procesie MTM (methane to methanol). Przeprowadzone badania wykazały, że wprowadzenie srebra do katalizatorów palladowych powoduje zmiany w wartościach TPO (temperature-programmed oxidation) i TPD (temperature-programmed desorption). Stwierdzono, że zawartość srebra w katalizatorach wpływa w sposób istotny na pojawianie się niskotemperaturowych form aktywnego tlenu. Reakcja pełnego utleniania przebiega trudniej i następuje wzrost energii aktywacji. Aktywacja molekuły metanu jest zatem łatwiejsza na palladzie metalicznym niż na tlenkach.

Bimetallic Pd-Ag/Al2 O3 catalysts for partial oxidn. of MeH to MeOH were prepd. by impregnation method and studied for chemisorption of H2 and dispersion of metals in the catalyst grains. The addn. of Ag resulted in formation of active forms of O2. The full oxidn. of MeH was more difficult and an increase in the activation energy was obsd.

Wpływ preparatyki tlenkowych katalizatorów chromowych na przebieg odwodornienia propanu do propenu w obecności ditlenku węgla

63%

Michorczyk P. , Ogonowski J.

tom T. 82, nr 6

402-405