Magnesium as promoter of CO2 methanation on Ni-based USY zeolites

CO2 methanation was studied over Ni–Mg–USY zeolite catalysts. Mg was added by incipient wetness impregnation and ion exchange. Whatever the Mg incorporation method used, Mg is able to improve the performance of the Ni-zeolite catalysts. Magnesium impregnation at lower contents (below 2.5%) over a 5%Ni/zeolite leads to an enhancement of the CO2 conversion into methane of 15% at 350–450 °C, probably due to the induced increase of the Ni particle dispersion, as well as to the possible activation of CO2 on the defects present on the MgO surface. At higher Mg contents, the stronger interaction between Ni and Mg oxides, leading to the formation of NiO–MgO solid solutions, seems to reduce the reducibility of the Ni species, decreasing the amount of nickel active sites available and thus the catalytic performance. Furthermore, important improvements of the catalytic performance (CO2 conversion and CH4 selectivity increased around 20% at 350–450 °C) were also found for the Mg-exchanged 5%Ni/zeolite. The results are comparable to those obtained by impregnation, but lower Mg contents are required. The enhanced activation of CO2 on Mg2+, the more dispersed Ni particles on the support, as well as the enhanced Ni reducibility when compared to the impregnated catalysts can explain the observed results. The beneficial effect of the Mg addition both by impregnation and ion exchange was also observed for samples containing higher amounts of Ni, the best sample remaining stable after 10 h under reaction conditions. Thus, Mg could be an interesting promoter for CO2 methanation over Ni-zeolite catalysts

Management and outcomes in critically ill nonagenarian versus octogenarian patients

Background: Intensive care unit (ICU) patients age 90 years or older represent a growing subgroup and place a huge financial burden on health care resources despite the benefit being unclear. This leads to ethical problems. The present investigation assessed the differences in outcome between nonagenarian and octogenarian ICU patients. Methods: We included 7900 acutely admitted older critically ill patients from two large, multinational studies. The primary outcome was 30-day-mortality, and the secondary outcome was ICU-mortality. Baseline characteristics consisted of frailty assessed by the Clinical Frailty Scale (CFS), ICU-management, and outcomes were compared between octogenarian (80-89.9 years) and nonagenarian (>= 90 years) patients. We used multilevel logistic regression to evaluate differences between octogenarians and nonagenarians. Results: The nonagenarians were 10% of the entire cohort. They experienced a higher percentage of frailty (58% vs 42%; p < 0.001), but lower SOFA scores at admission (6 +/- 5 vs. 7 +/- 6; p < 0.001). ICU-management strategies were different. Octogenarians required higher rates of organ support and nonagenarians received higher rates of life-sustaining treatment limitations (40% vs. 33%; p < 0.001). ICU mortality was comparable (27% vs. 27%; p = 0.973) but a higher 30-day-mortality (45% vs. 40%; p = 0.029) was seen in the nonagenarians. After multivariable adjustment nonagenarians had no significantly increased risk for 30-day-mortality (aOR 1.25 (95% CI 0.90-1.74; p = 0.19)). Conclusion: After adjustment for confounders, nonagenarians demonstrated no higher 30-day mortality than octogenarian patients. In this study, being age 90 years or more is no particular risk factor for an adverse outcome. This should be considered- together with illness severity and pre-existing functional capacity - to effectively guide triage decisions