Title Pt nanoparticles-loaded and noble-metal-free, mesoporous oxides as efficient catalysts for CO2 hydrogenation and dry reforming with methane Short title Noble-metal-free, mesoporous oxides for CO2 activation reactions Article type Full Length Article

No abstract

The steam reforming of ethanol (SRE) is a key process for the production of H 2 and other vital hydrocarbons. The present work describes the synthesis of Platinum-Gallium (PtÀ Ga) nanoalloys supported on mesostructured cellular foam (MCF-17) via ultrasound-assisted impregnation method. Ga was substituted with Pt in different wt.% i. e. Pt/MCF-17, Pt 99.9 Ga 0.1 /MCF-17, Pt 99 Ga 1 /MCF-17, and Pt 90 Ga 10 /MCF-17 and was evaluated towards the SRE at a temperature range of 473K-773 K towards hydrogen (H 2 ), acetaldehyde (CH 3 CHO), diethylether (DEE), ethylene (C 2 H 4 ), carbon monoxide (CO), carbon dioxide (CO 2 ), methane (CH 4 ), and ethane (C 2 H 6 ). The SRE activity and H 2 formation rate with Pt 90 Ga 10 /MCF-17 catalyst were observed to be 68.1 % and 3047.2 nmole g À 1 sec À 1 , which is 9.8 and 4.5 times more than the Pt/MCF-17 counterparts. Moreover, as observed from DRIFTS, NH 3 -TPD and XPS studies Ga showed high interaction with Pt in the electron deficit state which resulted in the increased dehydrogenating and acidic properties that resulted in a higher yield of H 2 .

In the present study, NiO modified ZnAl 2 O 4 and ZnO modified NiAl 2 O 4 spinel along with pure Al 2 O 3 , ZnAl 2 O 4 and NiAl 2 O 4 for comparison in the CO 2 hydrogenation reaction have been investigated. It was found that NiAl 2 O 4 , NiO/ZnAl 2 O 4 and ZnO/NiAl 2 O 4 catalysts exhibited outstanding activity and selectivity towards methane even at high temperature compared to similar spinel structures reported in the literature. NiO/ZnAl 2 O 4 catalyst showed CO 2 consumption rate of ~ 19 μmol/g·s at 600 °C and ~ 85% as well as ~ 50% of methane selectivity at 450 °C and 600 °C, respectively. The high activity and selectivity of methane can be attributed to the presence of metallic Ni and Ni/NiO/ZnAl 2 O 4 interface under the reaction conditions as evidenced by the XRD results.

The ultrafiltration of whey solutions is a common feature of dairy processes. However, the frequent fouling of ultrafiltration membranes and the subsequent cleaning cycle significantly affects the economics of the process. In this work, we investigated the effect of ultrasonically assisted ultrafiltration. The ultrafiltration of whey solution was investigated in order to determine the main parameters affecting the flux, retention and membrane fouling. The experiments were carried out with an ultrasonic combined laboratory ultrafiltration device, using regenerated cellulose ultrafiltration membranes. The results showed that increasing resistance during filtration is predominantly caused by the concentration polarization, while the participation of membrane fouling in the total resistance is negligible. The ultrasonically assisted ultrafiltration actively reduces the concentration polarization layer resistance. The retention changed slightly with ultrasound power. PRACTICAL APPLICATIONSCombination of ultrasound and ultrafiltration processes in dairy industry may enhance the efficiency of whey separation processes during ultrafiltration of why solutions. The given model for describing the filtration mechanism and modified Reynolds number for ultrasonically assisted batch reactor allow the scale up of coupled ultrafiltration process for dairy industry.