Insights on a Methanation Catalyst Aging Process: Aging Characterization and Kinetic Study

Power to gas systems is one of the most interesting long-term energy storage solutions. As a result of the high exothermicity of the CO2 methanation reaction, the catalyst in the methanation subsystem is subjected to thermal stress. Therefore, the performance of a commercial Ni/Al2O3 catalyst was investigated over a series of 100 hour-long tests and in-process relevant conditions, i.e. 5 bar from 270 to 500 °C. Different characterization techniques were employed to determine the mechanism of the observed performance loss (N2 physisorption, XRD, TPO). The TPO analysis excluded carbon deposition as a possible cause of catalyst aging. The BET analysis evidenced a severe reduction in the total surface area for the catalyst samples tested at higher temperatures. Furthermore, a direct correlation was found between the catalyst activity decline and the drop of the catalyst specific surface. In order to correctly design a reliable methanation reactor, it is essential to have a kinetic model that includes also the aging kinetics. For this purpose, the second set of experiments was carried out, in order to determine the intrinsic kinetics of the catalyst. The kinetic parameters were identified by using nonlinear regression analysis. Finally, a power-law aging model was proposed to consider the performance loss in time

Catalytic vs electrocatalytic reduction of CO2 to added-value products

Currently, around 85% of the energy matrix is dependent on fossil fuels. Burning fossil fuels provokes environmental pollutants such as CO2, which is the most representative GHG and its concentration has increased in the atmosphere after industrial revolution to >410 ppm[1]. Therefore, to mitigate CO2 emissions into the atmosphere, it can be exploited as a raw material to synthesize high added-value products (i.e. methanol) [2]. The electrochemical (EC) reduction of CO2 is a sustainable and technologically interesting process to produce chemicals or fuels using renewable electricity sources[3]. The main challenge is to find a suitable electrocatalyst to establish this technology at an industrial level. In such context, our group have exploited, for this EC process, a Cu-based material typically used as catalyst in Thermochemical (TC) catalysis for the production of methanol. A commercial catalyst (Cu-Zn-Al-based) was tested for both processes for comparison. The TC CO2 reduction reaction in H2 atmosphere (25 bars and 250 °C) leads to a methanol selectivity of 50% and CO as side-product, whereas the EC process (at atmospheric conditions) yields different alcohols and other C-based products (C1 to C3) with an overall faradaic efficiency of ~70%. The EX situ X-ray diffraction pattern, Field-Emission Electron Microscopy and Transmission Electron Microcopy of the catalyst were compared before and after both experiments in order to study the role of the modification of the catalyst components during operation in the final selectivity. These results demonstrated that there is synergy between both processes that can be exploited to develop new electrocatalysts

CO2 conversion into hydrocarbons via modified Fischer-Tropsch synthesis by using bulk iron catalysts combined with zeolites

To effectively address the challenges posed by global warming, a prompt and coordinated effort is necessary to conduct an extensive study aimed at reducing CO2 emissions and overcoming the obstacles presented by expensive and scarce fossil fuel resources. This study primarily focuses on comparing two different methodologies for preparing Na-promoted Fe3O4-based catalysts for the CO2 hydrogenation into hydrocarbon mixtures. Three catalysts were synthesized and tested: two samples were impregnated with a different amount of Na (1 wt% and 5 wt%), while a third one was obtained via coprecipitation with NaOH. As the latter catalyst exhibited the best performance, it was combined with zeolites in two ways: physical mixtures and core-shell structures. MFI-type zeolites were used in both configurations and a conventional structure was compared to a hierarchical one. As a result, mesopores increased successfully both the CO2 conversion from 37% to 40% and the liquid hydrocarbon (C6+) selectivity from 29% to 57%, doubling the C6+ yield. On the other hand, NH3-TPD and XPS measurements demonstrated that the intimate contact between the two materials in the core-shell structures led to the migration of Na from the oxide to the zeolite reducing the concentration of strong acid sites and, consequently, the liquid hydrocarbon yield

Physico-Chemical Modifications Affecting the Activity and Stability of Cu-Based Hybrid Catalysts during the Direct Hydrogenation of Carbon Dioxide into Dimethyl-Ether

The direct hydrogenation of CO2 into dimethyl-ether (DME) has been studied in the presence of ferrierite-based CuZnZr hybrid catalysts. The samples were synthetized with three different techniques and two oxides/zeolite mass ratios. All the samples (calcined and spent) were properly characterized with different physico-chemical techniques for determining the textural and morphological nature of the catalytic surface. The experimental campaign was carried out in a fixed bed reactor at 2.5 MPa and stoichiometric H2/CO2 molar ratio, by varying both the reaction temperature (200–300 °C) and the spatial velocity (6.7–20.0 NL∙gcat−1∙h−1). Activity tests evidenced a superior activity of catalysts at a higher oxides/zeolite weight ratio, with a maximum DME yield as high as 4.5% (58.9 mgDME∙gcat−1∙h−1) exhibited by the sample prepared by gel-oxalate coprecipitation. At lower oxide/zeolite mass ratios, the catalysts prepared by impregnation and coprecipitation exhibited comparable DME productivity, whereas the physically mixed sample showed a high activity in CO2 hydrogenation but a low selectivity toward methanol and DME, ascribed to a minor synergy between the metal-oxide sites and the acid sites of the zeolite. Durability tests highlighted a progressive loss in activity with time on stream, mainly associated to the detrimental modifications under the adopted experimental conditions

Warming-up the immune cell engagers (ICEs) era in breast cancer: state of the art and future directions

The advent of immune checkpoint inhibitors (ICIs) has deeply reshaped the therapeutic algorithm of triple-negative breast cancer (TNBC). However, there is considerable scope for better engagement of the immune system in other BC subtypes. ICIs have paved the way for investigations into emerging immunotherapeutic strategies, such as immune cell engagers (ICEs) that work by promoting efficient tumor cell killing through the redirection of immune system against cancer cells. Most ICEs are bispecific antibodies that simultaneously recognize and bind to both cancer and immune cells generating an artificial synapse. Major side effects are cytokine release syndrome, hepatotoxicity, and neurotoxicity related to inappropriate immune system activation. Here, we provide a comprehensive overview of this compounds, the available preclinical and clinical evidence supporting their investigation and development in BC also highlighting the challenges that have prevented their widespread use in oncology. Finally, major strategies are explored to broaden their use in BC