HETEROGENEOUS CATALYTIC DEOXYGENATION OF LIPIDS TO FUEL-LIKE HYDROCARBONS OVER IMPROVED BIMETALLIC NICKEL CATALYSTS

Diminishing petroleum reserves and environmental considerations have strengthened the demand for developing renewable fuel technologies. One alternative is deoxygenating plant oils, animal fats, and waste lipid streams to fuel-like hydrocarbons. These fuels offer a drop-in replacement to petroleum products while potentially becoming carbon neutral, satisfying both fuel and environmental concerns. This fuel is obtained through catalytic deoxygenation via either hydrodeoxygenation (HDO) or decarboxylation/ decarbonylation (deCOx). HDO requires problematic sulfided catalysts and extreme hydrogen pressures to convert lipids to fuel-like hydrocarbons. Therefore, this work focuses on the deCOx pathway, where hydrogen is not required for deoxygenation to take place. Generally, other authors use Pd or Pt as the active metals for deCOx; however, their cost can be industrially prohibitive. Recently, inexpensive Ni catalysts have shown comparable catalytic deCOx activity to Pd and Pt, albeit significant catalyst deactivation and catalytic cracking to undesirable products remain problematic. Therefore, this work aims to improve the activity, selectivity, and recyclability of supported Ni catalysts for the deCOx of lipids. Cu, Sn, and minimal amount of Pt were investigated as secondary promoter metals for Ni catalysts for deCOx. Deoxygenation of waste lipids such as brown grease and yellow grease was also accomplished in an industrially relevant fixed bed reactor

Continuous Catalytic Deoxygenation of Waste Free Fatty Acid-Based Feeds to Fuel-Like Hydrocarbons Over a Supported Ni-Cu Catalyst

While commercial hydrodeoxygenation (HDO) processes convert fats, oils, and grease (FOG) to fuel-like hydrocarbons, alternative processes based on decarboxylation/decarbonylation (deCOx) continue to attract interest. In this contribution, the activity of 20% Ni-5% Cu/Al2O3 in the deCOx of waste free fatty acid (FFA)-based feeds—including brown grease (BG) and an FFA feed obtained by steam stripping a biodiesel feedstock—was investigated, along with the structure-activity relationships responsible for Ni promotion by Cu and the structural evolution of catalysts during use and regeneration. In eight-hour experiments, near quantitative conversion of the aforementioned feeds to diesel-like hydrocarbons was achieved. Moreover, yields of diesel-like hydrocarbons in excess of 80% were obtained at all reaction times during a BG upgrading experiment lasting 100 h, after which the catalyst was successfully regenerated in situ and found to display improved performance during a second 100 h cycle. Insights into this improved performance were obtained through characterization of the fresh and spent catalyst, which indicated that metal particle sintering, alloying of Ni with Cu, and particle enrichment with Cu occur during reaction and/or catalyst regeneration

Effect of Cu and Sn promotion on the catalytic deoxygenation of model and algal lipids to fuel-like hydrocarbons over supported Ni catalysts

The ability of Cu and Sn to promote the performance of a 20% Ni/Al2O3 catalyst in the deoxygenation of lipids to fuel-like hydrocarbons was investigated using model triglyceride and fatty acid feeds, as well as algal lipids. In the semi-batch deoxygenation of tristearin at 260 °C a pronounced promotional effect was observed, a 20% Ni-5% Cu/Al2O3 catalyst affording both higher conversion (97%) and selectivity to C10-C17 alkanes (99%) in comparison with unpromoted 20% Ni/Al2O3 (27% conversion and 87% selectivity to C10-C17). In the same reaction at 350 °C, a 20% Ni-1% Sn/Al2O3 catalyst afforded the best results, giving yields of C10-C17 and C17 of 97% and 55%, respectively, which contrasts with the corresponding values of 87 and 21% obtained over 20% Ni/Al2O3. Equally encouraging results were obtained in the semi-batch deoxygenation of stearic acid at 300 °C, in which the 20% Ni-5% Cu/Al2O3 catalyst afforded the highest yields of C10-C17 and C17. Experiments were also conducted at 260 °C in a fixed bed reactor using triolein − a model unsaturated triglyceride − as the feed. While both 20% Ni/Al2O3 and 20% Ni-5% Cu/Al2O3 achieved quantitative yields of diesel-like hydrocarbons at all reaction times sampled, the Cu-promoted catalyst exhibited higher selectivity to longer chain hydrocarbons, a phenomenon which was also observed in experiments involving algal lipids as the feed. Characterization of fresh and spent catalysts indicates that Cu enhances the reducibility of Ni and suppresses both cracking reactions and coke-induced deactivation

A systematic review of water vulnerability assessment tools

The important relationship between health and water necessitates consideration of water vulnerability. Water vulnerability is contingent upon biophysical and social drivers operating at multiple scales, and is difficult to assess. This paper offers a systematic review of 50 water vulnerability assessment tools. We identify and synthesise the contents of these assessment tools (710 indicators) into five dimensions and 22 sub-dimensions and consider the extent to which they reflect environmental and social aspects. The findings are discussed in light of a holistic approach to water resources management, and specifically Integrated Water Resources Management (IWRM). Significant opportunities exist to enhance the efficacy of water vulnerability assessment tools by incorporating indicators and operational measures for social considerations (e.g., adaptation, institutions, governance) that are developed outside the context of water.AuthorCount:3;</p

Kawasaki Disease Complicated by Salmonella oranienburg Coinfection

Kawasaki disease is a medium vessel vasculitis with a multisystem presentation affecting 9–20 per 100,000 children under 5 years of age in the United States. Salmonella coinfection has not been previously described. We present a 12-month-old vaccinated male with Kawasaki disease in the setting of Salmonella bacteremia. Initial intervention for the Kawasaki disease with IVIG was ineffective, prompting adjunctive therapy with anakinra, with eventual full recovery. Concurrent Kawasaki disease and bacteremia may confound diagnosis and necessitate nontraditional treatment approaches

DataFile_SalamanderDispersal

Ringed salamander dispersal data collected from a field experiment conducted at Fort Leonard Wood, Missouri, USA. All metadata are in the .csv

Effect of Pt Promotion on the Ni-Catalyzed Deoxygenation of Tristearin to Fuel-Like Hydrocarbons

Pt represents an effective promoter of supported Ni catalysts in the transformation of tristearin to green diesel via decarbonylation/decarboxylation (deCOx), conversion increasing from 2% over 20% Ni/Al2O3 to 100% over 20% Ni-0.5% Pt/Al2O3 at 260 &#176;C. Catalyst characterization reveals that the superior activity of Ni-Pt relative to Ni-only catalysts is not a result of Ni particle size effects or surface area differences, but rather stems from several other phenomena, including the improved reducibility of NiO when Pt is present. Indeed, the addition of a small amount of Pt to the supported Ni catalyst dramatically increases the amount of reduced surface metal sites, which are believed to be the active sites for deCOx reactions. Further, Pt addition curbs the adsorption of CO on the catalyst surface, which decreases catalyst poisoning by any CO evolved via decarbonylation, making additional active sites available for deoxygenation reactions and/or preventing catalyst coking. Specifically, Pt addition weakens the Ni-CO bond, lowering the binding strength of CO on surface Ni sites. Finally, analysis of the spent catalysts recovered from deCOx experiments confirms that the beneficial effect of Pt on catalyst performance can be partially explained by decreased coking and fouling

Epigenetic control of cellular crosstalk defines gastrointestinal organ fate and function

Mesenchymal-epithelial crosstalk plays a key role in gut development and stem cell homeostasis, though underlying mechanisms are still unclear. Here, the authors demonstrate that mesenchymal Polycomb Repressive Complex 2 controls niche signals for gut epithelial fate and growth