The etherification with methanol of C5 and C6 compounds present in FCC light gasoline was studied. The catalyst used in the experiments was a cation-exchange resin, and the temperature range was ...323−353 K. The initial etherification rates were measured in a batch reactor. The reactivities of the alkenes were compared by calculating the rate constants. The rate constant of 1-methylcyclopentene was the highest for the C6 compounds. The effects of thermodynamic limitations on the etherification of FCC light gasoline were studied in a plug flow reactor. The thermodynamic limitations were significant for 1-methoxy-1-methylcyclopentane above 323 K and for the formation of the other C6 methyl ethers at temperatures above 333 K. The experimental equilibrium constants were calculated at temperatures of 343 and 353 K and the values compared with the published values.
Small molecular weight nuclear RNAs (SnRNA) purified from the chromatin of SV40-transformed W138 human fibroblasts have been found to stimulate transcription of chromatin in homologous isolated ...nuclei as well as in nuclei of untransformed human and monkey cells. Stimulation in normal cell nuclei involves an increase in both initiation sites and rate of elongation of RNA chains. Fractionation of the SnRNA in polyacrylamide gradient slab gels revealed that the "active" RNA was 160-175 nucleotides in length.
Regeneration kinetics of a cracking catalyst was studied by temperature programmed oxidation (TPO) in a microreactor system. The CO and CO
2 responses were detected as a function of time while ...heating the sample at a constant rate. Different oxygen concentrations (0.5–2.0%) and heating rates (5 and
10
K/
min
) were applied. Three kinetic models were tested and the parameters were estimated by non-linear regression. The models were capable of describing the experimental data adequately and the parameters were physically acceptable.
Since the 1970s the application of probabilistic methods to power system analysis was addressed in many papers. Main objective was and still is to find a probabilistic counterpart to the ...deterministic Load Flow Calculation techniques that can cope with uncertainty about the grid usage. The term "Classical Probabilistic Load Flow Problem" refers to the problem to determine probability information about a line's absolute current from the probability information about nodal powers. Until now approaches that use model simplifications leading to inherent imprecision were used to address this problem. In this paper the authors present a novel approach that allows for the exact solution of the before described `Classical Probabilistic Load Flow Problem' based on a full-steady state AC-network model.
The differential conversions and equilibrium composition in the etherification of isobutene with 1-propanol and 2-propanol were measured. A macroreticular, strong cation exchange resin was used as a ...catalyst. A plug flow reactor was used for differential experiments and a batch reactor for the equilibrium experiments.
In the differential experiments the only side reaction observed was the dimerisation of the isobutene. The etherification and dimerisation reactions were dependent on temperature and on the isobutene/alcohol mole ratio. Both reactions were faster with 1-propanol than with 2-propanol, which could be due to the different steric hindrance of the reacting alcohols or forming intermediates. At a constant temperature the reaction rate of the etherification increased with the isobutene/alcohol mole ratio, reached a maximum value and then started to decrease.
The equilibrium constants for the formation of propyl-
tert-butyl ether (PTBE) and iso propyl-
tert-butyl ether (IPTBE) from 1-propanol, 2-propanol and isobutene were measured in a batch reactor at temperatures of 313–353
K. As for the reaction rates in the differential experiments, the equilibrium constants were also significantly lower in the formation of IPTBE than in the formation of PTBE. The standard enthalpy and entropy change of the reaction were calculated from the equilibrium results to be −26.4
kJ
mol
−1 and −53.0
J
mol
−1K
−1 for the formation of PTBE and −25.5
kJ
mol
−1 and −71.3
J
mol
−1K
−1 for the formation of IPTBE, respectively.
A novel microscale test method was developed for testing catalysts. A pyrolyser connected to a gas chromatograph was used for pyrolysing the biomass sample and for leading the pyrolysis vapours ...through the catalyst for instant analysis. The injection port of the gas chromatograph was used as a fixed-bed catalyst reactor. Detection of reaction products was carried out with an atomic emission detector to quantify the various elements or with a mass selective detector to identify the compounds.
The test method was applied to treating pyrolysis vapours of Scots pine sawdust with ZnO, MgO, dolomite and limestone. Mass balances for carbon and hydrogen were determined with and without the catalyst. The carbon yields in liquid fraction decreased with all the catalysts studied. The highest yields were obtained with ZnO. Product distribution in pyrolysis vapours was rather similar with ZnO or without any catalyst. With MgO, dolomite and limestone, the compounds of pyrolysis vapours comprised mainly gases, water and degradation products of polysaccharides as well as some aromatic hydrocarbons.
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