Operando sulfur speciation during sulfur poisoning-regeneration of Ru/SiO2 and Ru/Al2O3 using non-resonant sulfur Kα1,2 emission

A periodic oxidative regeneration of a sulfur-poisoned methanation catalyst is an alternative to the expensive state-of-the-art process of syngas cleaning using wet scrubbers. Here we have employed operando X-ray emission spectroscopy (XES) to study sulfur speciation on Ru/SiO₂ and Ru/Al₂O₃ during methanation in the presence of H₂S and subsequent regeneration in dilute O₂ at 360 °C. XES allowed us to obtain semi-quantitative sulfur speciation and to monitor changes in the absolute sulfur concentration. It was established that Al₂O₃, in contrast to SiO₂, forms sulfite/sulfate species by reacting with SO₂, which is released from the poisoned Ru surface upon oxidative treatment. The concentration of sulfite/sulfate species is reduced upon switching the feed to H₂/CO while no simultaneous increase in sulfide concentration is observed. For both catalysts, the regenerative treatment removes adsorbed sulfur as SO₂ only partially, which we propose is the main reason for the incomplete activity recovery of the poisoned catalyst after regeneration.

Operando S Kα X-ray emission spectroscopy allows for a quantitative understanding of the sulfur poisoning and regeneration mechanism of state-of-the-art methanation catalysts used for the wood to synthetic natural gas process.     

Ruthenium on phosphorous-modified alumina as an effective and stable catalyst for catalytic transfer hydrogenation of furfural

Supported ruthenium was used in the liquid phase catalytic transfer hydrogenation of furfural. To improve the stability of Ru against leaching, phosphorous was introduced on a Ru/Al₂O₃ based catalyst upon impregnation with ammonium hypophosphite followed by either reduction or calcination to study the effect of phosphorous on the physico-chemical properties of the active phase. Characterization using X-ray diffraction, solid state ³¹P nuclear magnetic resonance spectroscopy, X-ray absorption spectroscopy, temperature programmed reduction with H₂, infrared spectroscopy of pyridine adsorption from the liquid phase and transmission electron microscopy indicated that phosphorous induces a high dispersion of Ru, promotes Ru reducibility and is responsible for the formation of acid species of Brønsted character. As a result, the phosphorous-based catalyst obtained after reduction was more active for catalytic transfer hydrogenation of furfural and more stable against Ru leaching under these conditions than a benchmark Ru catalyst supported on activated carbon.

Phosphorous induces structural changes in Ru/Al₂O₃ that make it more active and more stable for liquid phase hydrogenation of furfural.     

Impacted morsellized bone grafting and cemented primary total hip arthroplasty for acetabular protrusion in patients with rheumatoid arthritis: An 8- to 18-year follow-up study of 36 hips

Between 1979 and 1989, we performed 36 primary total hip replacements in 31 rheumatoid arthritis patients with protrusio acetabuli. The deficient acetabulum was reconstructed with autologous morsellized bone grafts from the femoral head. 3 patients were lost to follow-up. 12 patients (13 hips) died within 8 years postoperatively, none had a revision. 16 patients (20 hips) were reviewed at an average follow-up of 12 (8-18) years. In 2 hips, a revision was performed for aseptic loosening of the acetabular component, 6.5 and 8 years after primary surgery, which means a 90% (95% CI: 77%-100%) survival rate at 12 years (Kaplan Meier analysis). This technique is a good option in cases with protrusio acetabuli due to rheumatoid arthritis.