NOPR Collection:

Extended Huckel molecular orbital calculations on anionic units simulated for heteropoly acid catalysts

Fri, 01 Jun 1990 00:00:00 GMT

Title: Extended Huckel molecular orbital calculations on anionic units simulated for heteropoly acid catalysts Authors: Viswanathan, B Abstract: Extended Huckelmolecularorbital calculations on simulated anions of heteropoly acids have been made to rationalize the order of acidities, oxidizing power and stabilities of these catalysts. Page(s): 509-511

Criteria for determining the mechanisms of solid state reactions from non-isothermal data

Fri, 01 Jun 1990 00:00:00 GMT

Title: Criteria for determining the mechanisms of solid state reactions from non-isothermal data Authors: Somasekharan, K N Abstract: A comprehensive procedure for analyzing sets of dynamic data collected at various rates of heating, and two powerful criteria for ascertaining the mechanism are given. (1) The kinetic parameters are first derived by linearizing {In [g(ɑ)] - In[p*(x).T²]} versus l/T. (2) The correct activation energy (E*) is then computed, without invoking the mechanism, by linearizing {In(q) -In[p*(x).T²]} versus l/T; by comparing the correct E* with the values computed in the first step, the correct mechanism may be identified. (3) Finally, using the correct E*, the pre-exponential factors (A) are computed for different mechanistic functions, from the intercept of the above fit; by comparing the A-values computed in the first and third steps, the mechanism can be established unequivocally. Page(s): 512-514

n-Butylamine and 1-butene adsorption on molybdena and tungsta hydrodesulfurisation catalysts promoted by nickel and cobalt

Fri, 01 Jun 1990 00:00:00 GMT

Title: n-Butylamine and 1-butene adsorption on molybdena and tungsta hydrodesulfurisation catalysts promoted by nickel and cobalt Authors: Alias, M O; Srinivasan, V Abstract: Adsorption of n-butylamineand 1-butene on Co and Ni promooted molybdena and tungsta catalysts has been studied to determine surface acid properties in relation to their desulfurisation reactivity. On examining the effect of Ni content on the adsorption capacity of n-butylamine adsorption sites on Ni-Mo catalysts and its relation to catalytic activity, it is found that n-butylamine adsorption at 90°C is linearly related to activity data. On comparing the n-butylamine adsorption results obtained on molybdena catalysts and tungsta catalysts, it is observed that molybdena catalysts have better acid properties consistent with their higher desulfurisation activity. 1-Butene adsorption results obtained for Ni and Co promoted molybdena and tungsta catalysts show that nickel molybdena catalysts with greater desulfurisation activity have higher 1-butene adsorption as compared to promoted tungsta catalysts. Page(s): 515-521

Mechanism of methanol synthesis on copper/zinc oxide/chromia catalyst

Fri, 01 Jun 1990 00:00:00 GMT

Title: Mechanism of methanol synthesis on copper/zinc oxide/chromia catalyst Authors: Selvanathan, A; Viswanathan, B; Kuriacose, J C Abstract: The methanol synthesis catalyst Cu/ZnO/Cr₂O₃ is studied using IR and diffuse reflectance spectroscopy (DRS) and temperature programmed desorption (TPD) techniques. DRS shows copper to be present as Cuᵒ and Cu⁺. IR spectrum of adsorbed CO shows two bands. one due to linear adsorption on a single site and the other due to bridge-type adsorption. The TPD of adsorbed CO shows two desorption regions, one in the temperature range of 300 - 400K and another above 540K with readsorption taking place between 400 and 500K. The TPD of H₂ also shows two desorption regions. CO is considered to be adsorbed on Cu and H2 on ZnO. The TPD of co-adsorbed CO and H₂ indicates interaction between CO and H₂. IR spectroscopic study of methanol decomposition suggests that the decomposition involves methoxide and formate intermediates. A mechanism is proposed for the synthesis reaction. Page(s): 522-527