Track A Basic Science

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/138319/1/jia218438.pd

Chlorinated alumina as an alkylation catalyst: influence of superficial HCl

International audienceChlorinated alumina catalysts were obtained by reacting gamma-alumina with gaseous CCl4 or hydrogen chloride under various conditions. They had chlorine contents between 4 and 6% by weight, and differed in surface acidity. They were tested as catalysts for the alkylation of isobutane with 2-butene using a fixed bed plug flow reactor. Alumina reacted with CCl4 was found inefficient for this reaction. However, the solid chlorinated with HCl above 800 K was able to catalyze alkylation at a temperature as low as 273 K. Moreover, the CCl4-reacted solid could be activated upon further treatment with HCl at moderate temperatures (370 to 550 K). However, the catalytic activity decays after a few hours on stream. The composition of the alkylate varied somewhat with time on stream: large amounts of cracked products appeared during the initial period, after which the selectivity to trimethylpentanes (TMP) was comparable to that of other solid catalysts. The presence of hydrogen chloride bound to the catalyst surface was established by measuring the temperature-programmed desorption (TPD) of HCl from the various Al2O3–Cl. For the active catalysts, desorption started at temperatures (350–400 K) well under those for the CCl4-treated sample, but all solids continuously released HCl above 650 K. Thus, HCl interacts with particular Lewis acid sites of Al2O3–Cl, and creates the strong Brønsted sites required for catalytic alkylation

Chlorinated alumina as an alkylation catalyst: influence of acidity moderators

International audienceChlorinated alumina catalysts obtained by reacting a gamma-alumina with hydrogen chloride show high initial activity in isobutane-butene alkylation. After a few hours on stream however, the conversion decays due to self poisoning. This work attempts at improving the catalyst lifetime by modifying the Al2O3-Cl catalyst. Best results were obtained by adding small amounts of alkaline cations to the alumina before chlorination. For a particular cation, lithium or sodium, the improvement in catalyst lifetime depends on the chlorination procedure (pre-treatment with CCl4, final temperature). Addition of cations also enhances the selectivity for octanes, mainly by decreasing the amount of cracked products. Degradation of 2,2,4-trimethylpentane was found to occur over the Al2O3-Cl catalysts at 273 K. The influence of cation addition on this process was examined. Thus, the occurrence of dimethylhexanes and cracked or heavier alkanes among alkylation products may be explained by the degradation of 2,2,4-TMP

In-flight fast-timing measurements in 152Sm

We report on the first application of in-flight fast-timingmeasurements, a method developed in order to directly measure lifetimes in the picosecond to nanosecond range. As a proof of principle of the method, lifetimes of the states belonging to the ground-state band in 152Sm are measured up to the 8+ 1 state. An excellent agreement with recommended values is found. A slightly improved determination of the spectroscopic quadrupole moment of the 4+ 1 state is also reported. In-flight fast-timing measurements open interesting opportunities for future studies of collective properties in radioactive nuclei

Very Long-Term Complete Remission Can Be Achieved in Men With High-Risk Localized Prostate Cancer and a Very High PSA Value: An Analysis of the GETUG 12 Phase 3 Trial.

Serum prostate specific antigen (PSA) is a well-known prognostic parameter in men with prostate cancer. The treatment of men with very high PSA values and apparently no detectable metastases is not fully established. Ancillary analysis from the GETUG 12 phase 3 trial. Patients with non-metastatic high-risk prostate cancer by bone and computerized tomography (CT) scan were randomly assigned to receive androgen deprivation therapy (ADT) and docetaxel plus estramustine or ADT alone. Relapse-free survival (RFS), clinical RFS, metastases-free survival (MFS), overall survival (OS), and prostate cancer-specific survival (PCSS) were estimated using the Kaplan-Meier method for different levels of PSA (50 ng/mL, 75 ng/mL, and 100 ng/mL). The relationship between PSA and outcomes was studied using residual-based approaches and spline functions. The median follow-up was 12 years (range: 0-15.3). Baseline PSA (<50 ng/mL, n = 328; ≥50ng/mL, n = 85) was associated with improved RFS (P = .0005), cRFS (P = .0024), and MFS (P = .0068). The 12-year RFS rate was 46.33% (CI 40.59-51.86), 33.59% (CI 22.55-44.97), and 11.76% (1.96-31.20) in men with PSA values <50 ng/mL (n = 328), 50-100 ng/mL (n = 68), and ≥100 ng/mL (n = 17), respectively. Exploratory analyses revealed no deviation from the linear relationship assumption between PSA and the log hazard of events. Men with apparently localized prostate cancer and a high baseline PSA value have a reasonable chance of being long-term disease-free when treated with curative intent combining systemic and local therapy