Hexagonální mezoporézní titanosilikáty jako nosič pro oxidy vanadu-Nadějné katalyzátory pro oxidativní dehydrogenaci n-butanu

The comparative study of structural properties and catalytic performance of V-containing high-surface mesoporous silica and mesoporous titanosilicate materials (HMS, Ti-HMS) in oxidative dehydrogenation of n-butane (C-4-ODH) was carried out. The aim of the study was to investigate effect of different titanium amount incorporated into silica support on the texture, speciation of vanadium complexes and its impact on catalytic performance. Prepared catalysts were characterized by XRF for determination of vanadium content, DTA/TG for thermal stability of matrix, XRD, SEM and N-2-adsorption for study of morphology and texture, FT-IR and DR UV-vis spectroscopy for verification of successful incorporation of Ti to the matrix and H-2-TPR and DR UV-vis spectroscopy for determination of vanadium complex speciation. All prepared materials were tested in n-butane ODH reaction at 460 degrees C. We conclude that titanium was successfully incorporated into mesoporous structure, which was preserved at least up to 600 degrees C. Catalytic activities of V-Ti-HMS catalysts were approximately four times higher than activity of V-HMS catalyst in spite of the fact that all samples exhibit the same amount of vanadium species with similar distribution. The selectivity to desired products was comparable for all catalysts. Enhanced catalytic activity of V-Ti-HMS materials allows activating of n-butane at significantly lower temperature (by 100 degrees C) compare with V-HMS materials.Srovnávací studie strukturních vlastností a katalytického výkonu V-obsahujících mezoporézních silik s vysokým povrchem a mezoporézních titanosilikátů (HMS, Ti-HMS) v oxidativní dehydrogenaci n-butanu byla provedena. Cílem studie bylo prozkoumat efekt odlišného množství titanu inkorporovaného do nosiče na texturu, komplexy vanadu a jejich vliv na katalytický výkon

Hexagonální mezoporézní titanosilikáty jako nosič pro oxidy vanadu-Nadějné katalyzátory pro oxidativní dehydrogenaci n-butanu

The comparative study of structural properties and catalytic performance of V-containing high-surface mesoporous silica and mesoporous titanosilicate materials (HMS, Ti-HMS) in oxidative dehydrogenation of n-butane (C-4-ODH) was carried out. The aim of the study was to investigate effect of different titanium amount incorporated into silica support on the texture, speciation of vanadium complexes and its impact on catalytic performance. Prepared catalysts were characterized by XRF for determination of vanadium content, DTA/TG for thermal stability of matrix, XRD, SEM and N-2-adsorption for study of morphology and texture, FT-IR and DR UV-vis spectroscopy for verification of successful incorporation of Ti to the matrix and H-2-TPR and DR UV-vis spectroscopy for determination of vanadium complex speciation. All prepared materials were tested in n-butane ODH reaction at 460 degrees C. We conclude that titanium was successfully incorporated into mesoporous structure, which was preserved at least up to 600 degrees C. Catalytic activities of V-Ti-HMS catalysts were approximately four times higher than activity of V-HMS catalyst in spite of the fact that all samples exhibit the same amount of vanadium species with similar distribution. The selectivity to desired products was comparable for all catalysts. Enhanced catalytic activity of V-Ti-HMS materials allows activating of n-butane at significantly lower temperature (by 100 degrees C) compare with V-HMS materials.Srovnávací studie strukturních vlastností a katalytického výkonu V-obsahujících mezoporézních silik s vysokým povrchem a mezoporézních titanosilikátů (HMS, Ti-HMS) v oxidativní dehydrogenaci n-butanu byla provedena. Cílem studie bylo prozkoumat efekt odlišného množství titanu inkorporovaného do nosiče na texturu, komplexy vanadu a jejich vliv na katalytický výkon

Chain-growth copolymerization of functionalized ethynylarenes with 1,4-diethynylbenzene and 4,4′-diethynylbiphenyl into conjugated porous networks

We report the synthesis of conjugated highly cross-linked polyacetylene-type networks with a high content of functional groups (-CH2OH, -NO2, -Ph2N, content up to 3.9 mmol/g) via a chain-growth copolymerization of either 1,4-diethynylbenzene or 4,4′-diethynylbiphenyl with functionalized mono- and diethynylbenzenes. The backbone of the networks consists of substituted polyene main chains that are cross-linked by arylene links. The optimized combinations of comonomers in the feed provide functionalized networks with a Brunauer-Emmett-Teller specific surface area up to 667 m2/g and enhanced affinity for CO2 adsorption (compared to the non-functionalized hydrocarbon networks of the same type). The dependence of the specific surface area of the networks on the size and architecture of the comonomers used for the synthesis is discussed in the paper. The reported networks can be classified into the group of conjugated microporous polymers (CMPs). Contrary to the CMPs synthesized by step-growth couplings, significantly lower average comonomer functionality in the feed (f = 1.5-2.0) is sufficient for the high specific surface area to be achieved in the reported polyacetylene-type CMPs. © 2015 Elsevier Ltd. All rights reserved.15-09637S, GACR, Czech Science FoundationCzech Science Foundation [15-09637S]; Science Foundation of Charles University [574612 B-CH, 580214]; National Budget of Czech Republic [CZ.1.05/2.1.00/03.0111]; European Regional Development Fund; Operational Program Research and Development for Innovation

Microporous conjugated polymers via homopolymerization of 2,5-diethynylthiophene

Homopolymerizations of 2,5-diethynylthiophene into conjugated microporous polymers by (i) chain-growth polymerization and (ii) polycyclotrimerization are described. Both methods provide nearly quantitative yields of thiophene-rich (7.6 mmol thiophene rings/g) networks with specific surface area up to 839 m2/g. The thiophene units enhance the affinity of the networks to CO2 and red-shift the UV/vis and fluorescence absorption and emission bands of the networks, respectively. © 2017 Elsevier Ltd15-09637S, GACR, Grantová Agentura České RepublikyCzech Science Foundation [15-09637S]; Ministry of Education, Youth and Sports [NPU I (LO1504)]; Slovak Research and Development Agency APVV [APVV-15-0545

Microporous conjugated polymers via homopolymerization of 2,5-diethynylthiophene

Homopolymerizations of 2,5-diethynylthiophene into conjugated microporous polymers by (i) chain-growth polymerization and (ii) polycyclotrimerization are described. Both methods provide nearly quantitative yields of thiophene-rich (7.6 mmol thiophene rings/g) networks with specific surface area up to 839 m2/g. The thiophene units enhance the affinity of the networks to CO2 and red-shift the UV/vis and fluorescence absorption and emission bands of the networks, respectively. © 2017 Elsevier Ltd15-09637S, GACR, Grantová Agentura České RepublikyCzech Science Foundation [15-09637S]; Ministry of Education, Youth and Sports [NPU I (LO1504)]; Slovak Research and Development Agency APVV [APVV-15-0545