Indian Institute of Technology Madras

About: Indian Institute of Technology Madras is a facility organization based out in Chennai, Tamil Nadu, India. It is known for research contribution in the topics: Catalysis & Heat transfer. The organization has 20118 authors who have published 36499 publications receiving 590447 citations.

First observation of the P-wave spin-singlet bottomonium states h b(1P) and h b(2P)

Abstract: We report the first observations of the spin-singlet bottomonium states h(b)(1P) and h(b)(2P). The states are produced in the reaction e(+)e(-) --> h(b)(nP)pi(+)pi(-) using a 121.4 fb(-1) data sample collected at energies near the Y(5S) resonance with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. We determine M[h(b)(1P)] = (9898.2(-1.0-1.1)(+1.1+1.0)) MeV/c(2) and M[h(b)(2P)] = (10 259.8 +/- 0.6(-1.0)(+1.4)) MeV/c(2), which correspond to P-wave hyperfine splittings Delta M-HF = (+1.7 +/- 1.5) and (+0.5(-1.2)(+1.6)) MeV/c(2), respectively. The significances of the h(b)(1P) and h(b)(2P) are 5.5 sigma and 11.2 sigma, respectively. We find that the production of the h(b)(1P) and h(b)(2P) is not suppressed relative to the production of the Y(1S), Y(2S), and Y(3S).

Promoting effect of ceria on the physicochemical and catalytic properties of CeO2–ZnO composite oxide catalysts

Abstract: CeO2–ZnO composite catalysts prepared by amorphous citrate method have been investigated for cyclohexanol dehydrogenation and hydrogen transfer reactions. The precursors and catalysts have been characterized by TGA, CHN analysis, XRD, UV–vis–NIR diffuse reflectance, SEM and acid–base measurements. The amorphous precursors in citrate process contain one molecule of citric acid per Ce4+ or Zn2+ ions. Structural studies of composite oxides indicate the presence of individual oxide phases along with non-equilibrium solid solutions in a limited composition range. The composite oxides contain low coordination Ce3+ and Ce4+ sites. Cyclohexanone was obtained as main product for cyclohexanol transformation reaction carried out over these mixed oxide catalysts due to dehydrogenation on basic sites. The presence of ceria in the composite oxide enhances the surface area and acid–base properties facilitating the dehydrogenation process. At low ceria content, the CeO2–ZnO composite oxide catalysts show higher catalytic activity for both cyclohexanol dehydrogenation and hydrogen transfer reactions due to higher basicity, surface area and smaller crystallite sizes. Hydrogen transfer activity is found to be higher on CeO2(10%)–ZnO catalyst prepared by citrate method compared to the catalyst prepared by decomposition from acetate precursor. This study demonstrates the promoting effect of ceria in CeO2–ZnO catalysts for reactions involving acid–base sites.