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Abstract SUMMARY AND CONCLUSIONS 1- Pt and Ni NPs supported on alumina and /or silica (commercially supplied), synthesized via microwave assisted irradiation technique (MAS) exhibited higher surface areas, with lower pore dimensions especially for diluted samples improved dispersion profile and, better catalytic activity and selectivity, compared with those samples synthesized by traditional rotary chemical evaporation technique (RCE). 2- Electrical measurements confirmed that the electromagnetic radiations in MAS method enhance the even distribution of smaller in size Pt NPs accompanied with higher concentration of grain boundaries, generating highly mobile electrons and lattice vibrations (phonons), as compared with nanoparticles produced during RCE method. 3- The synthesized γ- alumina nanopowder as well as the alumina samples modified by CTAB and pluronic triblock (P123) had highly crystalline structure with cubic spinel lattice (space group Fd3m). Alumina modified by using 2.5 gm of CTAB (cationic surfactant) was chosen as a support for further study, as it exhibited higher surface parameters, lower pore dimensions and highest thermal stability. The reduction process proceeded through ultrasonic method (US) or microwave assisted solution irradiation (MAS). 4- Synthesized silica nanopowders and its modified samples by CTAB and P123 exhibited amorphous structure. Both parent silica (S 1 ) and modified one (S 1 C) were loaded with 0.9 wt% Pt or 5.0 wt% Ni in a sol-gel synthesis via ultrasonic (US) or microwave assisted solution irradiation (MAS). The S1 C (modified silica specifically by 2.5 gm CTAB) displayed low angle-XR diffraction characteristic of MCM-41 of hexagonal symmetry structure (P6mm), exhibiting high surface area, proper pore size distribution, well homogeneity and high thermal stability. 5- The 0.9 Pt/AC2.5 (MAS) nanocatalyst sample prepared by microwave assisted solution method) showed higher catalytic activity for n-hexane dehydrocyclization reaction into benzene than the same sample prepared by ultrasonic method (0.9 Pt/ AC2.5 (US)). On the other hand, the 5 Ni/AC 2.5 (MAS) was much more active for n-hexane cracking than the 5 Ni/ AC 2.5 (US) . 0.6 Pt/ S 1 C (US) exhibited higher catalytic activity towards n-hexane dehydrocyclization than 0.9Pt/S 1 C (MAS). The 5Ni/S1 (MAS) sample showed the much higher activity toward n-hexane cracking (96% at 450 ° C) than the same nanocatalyst prepared by US method (5Ni/S 1(US) ) (82% at 450 ° C). However, the 5Ni/S 1 C (US) displayed the highest cracking activity (94%), as compared with 5 Ni/ S1 C (MAS) (82%). 6- The catalytic activity for cyclohexane dehydrogenation increases by increasing both Pt content on modified alumina (AC 2.5 ) and modified silica (S 1 C) as well as with increasing the reaction temperature. The selectivity achieved 100% over the whole range of reaction temperatures for the catalyst samples prepared by the two techniques (MAS and US). - The 0.9 Pt/ AC2.5 (MAS) showed higher cyclohexane dehydrogenation activity (86% at 450 ° C) than the same sample prepared by US (0.9 Pt/ AC2.5 (US)) (75% at 450 ° C). - The 5Ni/AC2.5 (MAS) sample seemed more active than the same sample prepared by US (5Ni/AC2.5 (US) ). - The 0.9 Pt/S1 (US) (the parent silica nanopowder) was more active (75% benzene vs. 51% in case of 0.9 Pt/ S 1 (MAS) ). - The 0.9 Pt/S1 C (MAS) (modified silica nanopowder with 2.5 g CTAB) revealed higher dehydrogenation activity (83% benzene vs. 40 % in case of 0.9Pt/S 1C (US)). . - The 5 Ni/ S1 (US) and the corresponding 5Ni/ S 1 (MAS) showed nearly the same cyclohexane dehydrogenation trend. However, the 5Ni/ S1C (MAS) showed higher dehydrogenation activity than the 5Ni/ S 1 C (US). 7- In ethanol conversion, the 0.3 Pt/ AC 2.5 (US) sample was the most active for ethanol dehydration into ethylene (60% ethylene yield), compared with the other Pt loaded samples. . - Both the 5 Ni/ AC 2.5 (MAS) and 5 Ni/ AC 2.5 (US) nanocatalyst samples showed the same catalytic activity trend in ethylene production with little yield of acetaldehyde. - The 0.9 Pt/ S1 (US) was more active than 0.9 Pt/S1 (MAS) and the 5 Ni/ S 1 (MAS) was more active than 5 Ni/ S1 (US) for ethylene production. - The 0.9 Pt/ S1 C (MAS) was more active than the 0.9 Pt/ S1 C (US) . - Both 5 Ni/ S1 C (US) and 5 Ni/ S 1 C (MAS) were active in this reaction (yielding 61% ethylene in both cases over temperature range 350 ° C to 450 ° C. 8- The MIL-101 as a member of Cr- MOF family, had higher specific surface area ( SBET = 2100 m 2 /g ) , pronounced decrease in pore radius(< 2 nm) and extremely lower thermal stability up to 350 ° C than the other support systems under study (Al 2O3 & SiO2 ). ~ 75% wt losses were observed up to 570 ° C. This means that ~25% chromium oxide content was maintained in the Mil-101 framework. 9- The TEM image of Mil-101 and the corresponding Pt & Ni loaded samples showed cubo-octahedral crystals in shape of uniform size of ~ 212 nm. 10- The 0.9 Pt/ Mil-101 and 5 Ni / Mil-101 loaded samples were in situ reduced via RCE method. 11- in catalytic conversion of ethanol on these nano catalytic systems, the 5Ni/Mil-101 exhibited much higher activity than bare Mil-101 or 0.9 Pt/ Mil-101 toward ethylene production ( dehydration pathway) (59% yield) and 100% selectivity over whale range of temperature. It is to be mentioned that 0.9 Pt/ Mil-101 produced 46% ethylene at 300 ° C together with 11% acetaldehyde at 300 ° SUMMARY AND CONCLUSIONS 1- Pt and Ni NPs supported on alumina and /or silica (commercially supplied), synthesized via microwave assisted irradiation technique (MAS) exhibited higher surface areas, with lower pore dimensions especially for diluted samples improved dispersion profile and, better catalytic activity and selectivity, compared with those samples synthesized by traditional rotary chemical evaporation technique (RCE). 2- Electrical measurements confirmed that the electromagnetic radiations in MAS method enhance the even distribution of smaller in size Pt NPs accompanied with higher concentration of grain boundaries, generating highly mobile electrons and lattice vibrations (phonons), as compared with nanoparticles produced during RCE method. 3- The synthesized γ- alumina nanopowder as well as the alumina samples modified by CTAB and pluronic triblock (P123) had highly crystalline structure with cubic spinel lattice (space group Fd3m). Alumina modified by using 2.5 gm of CTAB (cationic surfactant) was chosen as a support for further study, as it exhibited higher surface parameters, lower pore dimensions and highest thermal stability. The reduction process proceeded through ultrasonic method (US) or microwave assisted solution irradiation (MAS). 4- Synthesized silica nanopowders and its modified samples by CTAB and P123 exhibited amorphous structure. Both parent silica (S 1 ) and modified one (S 1 C) were loaded with 0.9 wt% Pt or 5.0 wt% Ni in a sol-gel synthesis via ultrasonic (US) or microwave assisted solution irradiation (MAS). The S1 C (modified silica specifically by 2.5 gm CTAB) displayed low angle-XR diffraction characteristic of MCM-41 of hexagonal symmetry structure (P6mm), exhibiting high surface area, proper pore size distribution, well homogeneity and high thermal stability. 5- The 0.9 Pt/AC2.5 (MAS) nanocatalyst sample prepared by microwave assisted solution method) showed higher catalytic activity for n-hexane dehydrocyclization reaction into benzene than the same sample prepared by ultrasonic method (0.9 Pt/ AC2.5 (US)). On the other hand, the 5 Ni/AC 2.5 (MAS) was much more active for n-hexane cracking than the 5 Ni/ AC 2.5 (US) . 0.6 Pt/ S 1 C (US) exhibited higher catalytic activity towards n-hexane dehydrocyclization than 0.9Pt/S 1 C (MAS). The 5Ni/S1 (MAS) sample showed the much higher activity toward n-hexane cracking (96% at 450 ° C) than the same nanocatalyst prepared by US method (5Ni/S 1(US) ) (82% at 450 ° C). However, the 5Ni/S 1 C (US) displayed the highest cracking activity (94%), as compared with 5 Ni/ S1 C (MAS) (82%). 6- The catalytic activity for cyclohexane dehydrogenation increases by increasing both Pt content on modified alumina (AC 2.5 ) and modified silica (S 1 C) as well as with increasing the reaction temperature. The selectivity achieved 100% over the whole range of reaction temperatures for the catalyst samples prepared by the two techniques (MAS and US). - The 0.9 Pt/ AC2.5 (MAS) showed higher cyclohexane dehydrogenation activity (86% at 450 ° C) than the same sample prepared by US (0.9 Pt/ AC2.5 (US)) (75% at 450 ° C). - The 5Ni/AC2.5 (MAS) sample seemed more active than the same sample prepared by US (5Ni/AC2.5 (US) ). - The 0.9 Pt/S1 (US) (the parent silica nanopowder) was more active (75% benzene vs. 51% in case of 0.9 Pt/ S 1 (MAS) ). - The 0.9 Pt/S1 C (MAS) (modified silica nanopowder with 2.5 g CTAB) revealed higher dehydrogenation activity (83% benzene vs. 40 % in case of 0.9Pt/S 1C (US)). . - The 5 Ni/ S1 (US) and the corresponding 5Ni/ S 1 (MAS) showed nearly the same cyclohexane dehydrogenation trend. However, the 5Ni/ S1C (MAS) showed higher dehydrogenation activity than the 5Ni/ S 1 C (US). 7- In ethanol conversion, the 0.3 Pt/ AC 2.5 (US) sample was the most active for ethanol dehydration into ethylene (60% ethylene yield), compared with the other Pt loaded samples. . - Both the 5 Ni/ AC 2.5 (MAS) and 5 Ni/ AC 2.5 (US) nanocatalyst samples showed the same catalytic activity trend in ethylene production with little yield of acetaldehyde. - The 0.9 Pt/ S1 (US) was more active than 0.9 Pt/S1 (MAS) and the 5 Ni/ S 1 (MAS) was more active than 5 Ni/ S1 (US) for ethylene production. - The 0.9 Pt/ S1 C (MAS) was more active than the 0.9 Pt/ S1 C (US) . - Both 5 Ni/ S1 C (US) and 5 Ni/ S 1 C (MAS) were active in this reaction (yielding 61% ethylene in both cases over temperature range 350 ° C to 450 ° C. 8- The MIL-101 as a member of Cr- MOF family, had higher specific surface area ( SBET = 2100 m 2 /g ) , pronounced decrease in pore radius(< 2 nm) and extremely lower thermal stability up to 350 ° C than the other support systems under study (Al 2O3 & SiO2 ). ~ 75% wt losses were observed up to 570 ° C. This means that ~25% chromium oxide content was maintained in the Mil-101 framework. 9- The TEM image of Mil-101 and the corresponding Pt & Ni loaded samples showed cubo-octahedral crystals in shape of uniform size of ~ 212 nm. 10- The 0.9 Pt/ Mil-101 and 5 Ni / Mil-101 loaded samples were in situ reduced via RCE method. 11- in catalytic conversion of ethanol on these nano catalytic systems, the 5Ni/Mil-101 exhibited much higher activity than bare Mil-101 or 0.9 Pt/ Mil-101 toward ethylene production ( dehydration pathway) (59% yield) and 100% selectivity over whale range of temperature. It is to be mentioned that 0.9 Pt/ Mil-101 produced 46% ethylene at 300 ° C together with 11% acetaldehyde at 300 ° C. |