The transesterification reaction is the most utilized process to obtain biodiesel. Fried oil transesterification reactions with methanol have been studied using several zeolites Y and interchanged with CsCl and KOH. The reaction has been carried out both in a slurry reactor and a fixed bed catalytic reactor. The catalytic effects of zeolites have been tested within a temperature range of 60-476°C, 2.5-5% catalyst/waste oil weight ratio, and 6:1 - 100:1 methanol/oil molar ratio. Cosolvents (THF, n-hexane) in the reaction feedstock effect have also been studied as well as catalyst regeneration effects. Viscosity of both the oil and the transesterification reaction products was determined as an initial guide to investigate the degree of conversion to biodiesel as well as FAME content by GC. When interchanged zeolites are used conversions are improved, getting the best yields (98% FAME) for the Y756 zeolite interchanged with KOH. Viscosities of the reaction product obtained reached values next to diesel standard ones.
The effect of reaction/regeneration cycles on some structural
characteristics of a NiMo/Al2O3
hydrotreatment catalyst has been studied. The first regeneration
produces increases in pore
volume, porosity, and specific area. Above 5% coke deposit,
various changes in such properties
appear. Mo and Ni relative XPS intensities depend on the
reaction/regeneration cycles Ni
exposure decreases with them, whereas Mo exposure follows the opposite
trend. The effect of
coke on metal dispersion seems to be almost negligible. Coke
concentration proved to be the
variable which really influenced coke composition (H/C), independently
of the history of the
catalyst. The equation relating both variables is
H/C = 0.4378 + 1.342
exp[(−C
c/S
e)/0.059]
where
C
c is the percentage coke concentration and
S
e the specific surface area.
The aim of this study was to obtain a catalyst or support material from a natural pumice that could then be used in the hydroisomerization of n-pentane. Acid treatment of the raw material with HCl was found to extract a larger amount of cations than NH 4 Ac (Ac ) acetate), yielding a product with a better developed texture and structure. The total number of protons present in the solution affects potassium extraction, while sodium is affected by both factors of concentration and volume of dissolution independently. The specific area of the material (meters squared per gram) obtained depends on the treatment conditions, and it value can be calculated by means of the treatment condition variables or by the total number of moles of the cations extracted. The treatments could be carried out by working at and above ambient temperatures and with and without fresh acid replacements. The optimum treatment for obtaining a catalytic support was 10 mL/g of pumice of 3 M HCl for 10 h with three replacements of fresh acid working at 70 °C.
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