SANTINO, Letizia (Via Cicerone, Formia, I-04023, IT)
SANTINO, Letizia (Via Cicerone, Formia, I-04023, IT)
CLAIMS
1) CLAIM 1 the synthesis reactor with vertical axis, with forced recycle of reagents CO 2 and ethyl ether by mean of centrifugal compressor at magnetic dragging, with radial diffuser of the flux crossing the catalyzing complex composed by several porous septum, in series in the reactor entry lower part, working with a pressure between 15 bar and 55 bar and temperatures between 115°C and 235°C but preferably between 18 bar and 32 bar and between 140 0 C and 160 0 C.
2) CLAIM 2 the qualitative and quantitative catalyst composition of the reactor CLAIMED IN CLAIM 1 consisting in: a) potassium carbonate (K 2 CO 3 ) in powder between 80 and 200 mesh, with ponderal proportion from a 5% minimum to 35% maximum, but preferably around 15%. b) cobalt oxide (CoO) in powder between 140 and 230 mesh with ratio between 50 and 70 sqm/gram, from 3% and 25% but preferably around 10%. c) ethyl iodide (IC 2 H 5 ) with activator function, with proportion from 30% minimum and 85% maximum, but preferably around 75%.
3) CLAIM 3 the support of the catalyzing complex CLAIMED IN CLAIM 2 laid out in a shape of a circular ring consisting of alumina (Al 2 O 3 ) + active zeolite type 3 A in ponderal ratio between 1,2% and 3,5%.
4) CLAIM 4 the ponderal proportion between the support CLAIMED IN CLAIM 3 and the catalyzing complex that is from 30% minimum and 70% maximum, but preferably around 55%. 5) CLAIM 5 the manufacturing method and the layout of the catalyzing complex inside the reactor with the supports in circular configuration with central intake of the gaseous reagents recycle.
6) CLAIM 6 the ponderal ratio between the ethyl ether in reaction and the catalyzing complex from 1,5 minimum and 6,5 maximum, but preferably around 3,4. |
DESCRIPTION
of the industrial invention bearing the title
" Industrial production process of diethyl carbonate (DEC) by means of heterogeneous catalytic synthesis reactor fed by ethylic ether and carbon dioxide"
The organic carbonates are functional derivatives of carbonic acid and they are generally called dialkyl carbonates; thanks to their physical chemical characteristics they are subject of growing attention by the chemical industry and the plastic materials.
Recently the survey of the organic carbonates use is remarkably enlarged thanks to the property that these compounds show under the ambient and ecological point of view both for the industrial use and the production process.
Specifically the diethyl carbonate (DEC), obtained by the synthesis between ethylic ether and carbon dioxide, can use CO 2 coming from the sequestration of the thermal stations releases, aiding in such way the reduction of the CO 2 rate in the atmosphere and the reduction of greenhouse effect.
Moreover the ethylic ether used in the synthesis might derive from the dewatering of ethylic alcohol coming from the biomasses fermentation (no fossil origin), therefore the so obtained DEC might be considered as a renewable energetic vector.
The diethyl carbonate molecule shows some peculiar capacities inside the combustion chamber of endothermic motors because it is able to carry out an oxygenating and octaning vigorous action (octane number 124) within the field of additives for vehicles ecological fuels.
DEC, in small percentages in motor fuel (between 3% and 8%),causes a pulling down of polluting emissions and it is fully compatible with the basic fuels without showing out negative sides (toxicity, corrosion, volatility, low flammability point, clouding, solubility gaps).
The use of diethyl carbonate as organic solvent combines the best capacity of solvent action with a non-toxic behaviour and of easy storage (group III). For a large and massive use of this mixture (fuels reformulation, solvent, intermediate for urethanes and polycarbonates synthesis) it is necessary a low cost availability that can be obtained with a simple and efficient manufacture process. Some production processes are based on direct alcohol synthesis at high pressures, with long times of conversion, using toxic catalyses and expensive production plant. Other production processes are based on the indirect synthesis using as intermediate the ethyl carbonate (obtained from ethylene oxide plus CO 2 ), producing not only diethyl carbonate but also, as secondary product, ethyl glycol; moreover and above all these processes cannot profitably use ethyl alcohol coming from biomasses.
From the critical aspects of these processes it has appeared the necessity to develop a reactor for catalytic synthesis suitable to obtain large DEC quantities with high conversion yields, moderate pressures, limited temperatures and catalyses of simple construction. All these conditions are fundamental in order to obtain a considerable expense reduction of production plant and of product management. The tubular reactor with vertical axis, shown in Fig. 1, carries out the direct synthesis between ethyl ether (CH 3 CH 2 ) 2 O, introduced at liquid condition, and carbon dioxide CO 2 , introduced at gaseous condition in a temperature range between 115°C and 235°C and a pressure interval between 15 bar and 55 bar. So limited parameters values with consequent construction easiness are feasible thanks to the use of a catalytic complex able to carry out a high activity with the aid of reaction promoters.
The support typology and structure make easier the synthesis action of the catalyzing complex between CO 2 and ethyl ether molecules. The potassium carbonate along with the cobalt oxide and the ethyl iodide, absorbed on the support made by alumina and zeolite type 3A, quickly catalyze the DEC bonds formation.
The form of the catalytic complex consists of several circular rings with radial crossing of the gaseous stream during steam phase with reagent continuous recirculation through suitable centrifugal compressor at magnetic dragging.
This catalyst layout has a high permeability to gases (CO 2 specifically) as the support, after the impregnation and the mixing with the catalyzing complex, is put inside containers made with perforated stainless steel sheet and mesh net.
In this way there are the conditions for a homogeneous CO 2 diffusion over all the catalytic mass surface rendering very high the number of zone of contact between gaseous stream and active sites.
At reaction occurred it is necessary to act a first separation of the catalyst firm portion (K 2 CO 3 + alumina + zeolite) from the liquid portion constituted by DEC, not reacted ethyl ether and ethyl iodide.
Then it is necessary to act a fractional distillation of the liquid portion in order to separate the DEC and recover both the ether as reagent and the iodide as catalysis activator.
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