Influence of Contaminants in Steel Mill Exhaust Gases on Cu/ZnO/Al₂O₃ Catalysts Applied in Methanol Synthesis

The influence of impurities in steel mill exhaust gases on ternary Cu/ZnO/Al2O3 catalysts was studied for conventional methanol synthesis, which is one of the central reactions within the cross‐industrial approach of Carbon2Chem®. A series of hydrocarbons was identified as inert spectators for methanol synthesis. Several catalyst poisons like N‐containing compounds or O2 show reversible characteristics at low pressure. However, by increasing the partial pressure of O2, poisoning becomes irreversible, indicating different poisoning mechanisms concerning the reversibility of deactivation

Informing aerial total counts with demographic models: population growth of Serengeti elephants not explained purely by demography

Conservation management is strongly shaped by the interpretation of population trends. In the Serengeti ecosystem, Tanzania, aerial total counts indicate a striking increase in elephant abundance compared to all previous censuses. We developed a simple age-structured population model to guide interpretation of this reported increase, focusing on three possible causes: (1) in situ population growth, (2) immigration from Kenya, and (3) differences in counting methodologies over time. No single cause, nor the combination of two causes, adequately explained the observed population growth. Under the assumptions of maximum in situ growth and detection bias of 12.7% in previous censuses, conservative estimates of immigration from Kenya were between 250 and 1,450 individuals. Our results highlight the value of considering demography when drawing conclusions about the causes of population trends. The issues we illustrate apply to other species that have undergone dramatic changes in abundance, as well as many elephant populations

Evolution of zincian malachite synthesis by low temperature co-precipitation and its catalytic impact on the methanol synthesis

Low temperature co-precipitation enabled, for the first time, the preparation of phase pure zincian malachite precursors with Zn contents of up to 31 at.-%. The high Zn content was beneficial for maximizing the dispersion of Cu and oxygen defect sites on the ZnO surface. Further, an increase of the Zn loading from 10 to 31 at.-% doubled the specific surface areas obtained from N2O-RFC (Reactive Frontal Chromatography) and H-2-TA (Transient Adsorption). As the Zn content was increased from 10 to 31 at.-%, the apparent activation energy for methanol formation was strongly decreased. Furthermore, water formation was reduced indicating a retardation of the rWGS in favor of methanol formation at high Zn loadings. Additionally, compared to high temperature co-precipitation, low temperature precipitated catalysts exhibited increased catalytic activities

Structural analysis of hierarchically organized zeolites

Advances in materials synthesis bring about many opportunities for technological applications, but are often accompanied by unprecedented complexity. This is clearly illustrated by the case of hierarchically organized zeolite catalysts, a class of crystalline microporous solids that has been revolutionized by the engineering of multilevel pore architectures, which combine unique chemical functionality with efficient molecular transport. Three key attributes, the crystal, the pore and the active site structure, can be expected to dominate the design process. This review examines the adequacy of the palette of techniques applied to characterize these distinguishing features and their catalytic impact