Enhancement of distillate selectivity in Fischer-Tropsch synthesis by using iron and cobalt catalysts in a novel dual-bed reactor ?

Summary An integrated process for producing liquid fuels from synthesis gas via a two-stage Fischer-Tropsch (FT) reaction is disclosed. An iron catalyst was used in the first bed of a fixed-bed reactor followed by a ruthenium promoted cobalt catalyst in the second bed. The activity and selectivity of the dual-bed system were assessed and compared with those using catalysts in a single bed system, separately. The methane selectivity in the dual-bed reactor was about 11% less compared to that of the single-bed system. The C₅⁺ selectivity for the dual-bed reactor was 19.7% higher than that of the single-bed system.     

Synthesis of New Aza Thia Crowns Bearing 2,2′-Diaminodiphenyl Disulfide

Abstract

New aza thia crowns were prepared from the reaction of 2,2′-diaminodiphenyl disulfide and diacids or diacid chlorides. Diacids are malonic acid, adipic acid, sebacic acid, and 2,2′-thiodiacetic acid and diacid dichlorides are malonyl chloride, adipoyl chloride, sebacoyl chloride, and 2,2′-thiodiacetyl chloride.

[Supplementary materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfer, and Silicon and the Related Elements for the following free supplemental files: Additional figures.]     

Theoretical study of dihydrogen bonded clusters of water with tetrahydroborate

Ab initio calculations were used to analyze interactions of BH₄ ^? with 1?C4 molecules of H₂O at the MP2/6-311++G(d,p) and B3LYP/6-311++G(d,p) computational levels. The negative cooperativity for dihydrogen bond clusters containing H₂O···H₂O hydrogen bonds is more remarkable. The negative cooperativity is increased with increasing the size and also the number of hydrogen bonds in the cluster. The B?CH stretching frequencies show blue shifts with respect to cluster formation. Also greater blue shift of stretching frequencies where predicted for B?CH bonds which did not contribute in dihydrogen bonding with water molecules. The structures obtained have been analyzed with the Atoms in Molecules (AIM) methodology.     

Theoretical study of hydrogen and dihydrogen bond interaction of B6H10 with the HF molecule

Ab initio calculations were used to analyze the interactions of B₆H₁₀ with an HF molecule at the MP2/6-311++g(d,p) and B3LYP/6-311++g(d,p) computational levels. B₆H₁₀ could interact with HF through both its terminal (H_t) and bridged (H_b) hydrogens. The interaction of H_t and H_b of B₆H₁₀ with HF could result in the formation of H_t···H and H_b···F dihydrogen and hydrogen bond complexes, respectively. The obtained structures have been analyzed with the Atoms in Molecules methodology.