DE1768005C - Process for the production of ethylbenzene by thermal cleavage of dibenzyl - Google Patents

Description

The following example serves to explain the method according to the invention.

example

Several attempts have been made to thermally cleave dibenzyl in the presence of hydrogen. In each experiment, a solution consisting of dibenzyl and toluene in a ratio of 2 moles of toluene per mole of dibenzyl was pumped into a heated reactor together with 21 moles of hydrogen per mole of dibenzyl. The heated reactor was maintained at a pressure of about 49.2 kg / cm ² for each experiment. The flow to the reactor was adjusted so that an effective residence time of the reactants in the reactor of about 12 seconds was achieved. The following table shows the temperature used in each experiment and the conversions and yields achieved. The conversion is defined as the percentage of the dibenzyl fed to the reactor and converted into some other product. The yield is expressed as a percentage of the theoretical value, which is one mole of ethylbenzene per mole of dibenzyl converted.

Ver Reaction implementation yield search temperatiir of dibenzyl of ethylbenzene ίο No. ⁰ C V. 1 502 19.5 34.6 2 557 74.7 25.6 3 576 88.9 22.8 i5 4 599 97.6 18.6 5 626 98.7 12.7 6th 653 99.3 8.1

Claims (3)

a mononuclear, aromatic hydrocarbon, claims: is dissolved, wherein the amount of the solvent is 0.5 to 5.0 mol per mol of dibenzyi. 1. Process for the preparation before ethylbenzene Finally, there is another embodiment of the he by thermal cleavage of Dibenzyi in Gegen- 5 inventive method, was characterized by hydrogen under pressure, characterized in that the cleavage at about 450 to 650 ° C, a Vergekiert that one the cleavage in dwell time of 3 to 20 seconds, a pressure in the absence of a catalyst by heating about 14.1 to 141 kg / cm ² and in the presence of about 350 to 700 ¹ C for a dwell time of 3 to 25 mol of hydrogen per mole Dibenzyi will run from 1 to 30 seconds at a pressure between io. 7.03 and 352 kg / cm ² in present ·; from 1 to 40 months! The thermal fission in the presence of water Carries out hydrogen per mole of Dibenzyi. substance according to the present invention can be used 2. The method according to claim 1, characterized in that the temperature and pressure conditions are characterized in that the dibenzyi supplied to the cleavage zone are passed. In general, the temperature is at least partially maintained in a hydrocarbon in the range from about 400 to 700 ° C., preferably in a mononuclear, aromatic; Temperatures of about 450 to 65O ^c C, preferably hydrocarbon, is dissolved, the amount being. The pressure should generally be in the range of the solvent 0.5 to 5.0 mol per mol of Dibenzyi from about 7.03 to 352 kg, cm-. Preferably is. the pressure is in the range ν on about 14.1 to 141 kg cm ² . 3. The method according to claim 1 and 2, characterized in that 20 the hydrogen is in the cleavage zone quantities \ on characterized that the cleavage at about 450 to about 1 to 40 mol per mole of the cleavage zone supplied, 650 C, a residence time of 3 to 20 Seconds, dibenzyi be. Quantities of about 14.1 to 141 kg / cm ² and 3 to 25 moles of H ₂ per mole of dibenzyl are preferred. The presence of about 3 to 25 MoI hydrogen per hydrogen can be carried out with the Dibenzyi before the Em-MoI Dibenzyi. 25 line can be mixed into the crevice zone. However, it can also be fed separately. The residence time of the reactants in the reaction zone is generally between 1 and 30 seconds lie; A range of around ... 30 3 to 20 seconds. The invention relates to a method for Her- Dibenzyi is at normal room temperature production of ethylbenzene by thermal cleavage · solids. LJm its handling and its tran ^ To facilitate port of Dibenzyi in the presence of hydrogen, it is generally convenient ever Pressure. but not absolutely necessary - that the de The demand for styrene is constantly growing. 35 Dibenzyi fed to the cleavage zone at least partially The entire amount of the styrene currently produced is dissolved in a hydrocarbon solvent. practically comes from the dehydrogenation of Ethyoi- The hydrocarbon solvent can be benzene. A large part of the ethylbenzene used in styrene production can be either aromatic or non-aromatic, whereby the ethylbenzene used is obtained by alkylating, however, the aromatic solvents, preferably benzene, with ethylene. Turned 40 in the last few years. Particularly preferred are the mononuclear ones, ethylbenzene is increasingly also obtained in the case of aromatic solvents such as benzene, toluene or fractionation of petroleum. Furthermore, xylene. It is understandable that the hydrocarbon has recently been using dibenzyi as a starting material for the solvent from mixtures of various modifications of alkylbenzenes. This is how connections can exist. The amount of solvent used for the catalytic cleavage of Dibenzyi only needs to be so large that toluene has become known. In the USA patent the dibenzyi is partially solved. However, a catalytic method is also preferred so that the dibenzyi is completely dissolved. If the cleavage of Dibenzyi to toluene and ethylbenzene is used as a solvent, then it is written, but with considerably more Toluc! is obtained as an amount depending on the type of solvent in the general ethylbenzene. However, since the demand 5 ° mean between 0.5 to 5.0 moles per mole of Dibenzyi. for styrene and thus in turn the demand for preferred is the use of about 1 to 3 moles of ethylbenzene increases from year to year, according to hydrocarbon solvent per mole of dibenzene.
wanted new manufacturing process for ethylbenzene. To carry out the procedure according to The object of the present invention is a new type of plant used in the invention is not escaped for the production of ethylbenzene by thermal 55 separating; it can be a common thermal gap mixing Cleavage of Dibenzyi in the presence of plant can be used. It is only required. Hydrogen under pressure. that the plant the occurring in the reaction This object is withstood by the pressures and temperatures according to the invention and that it is achieved according to the method in that the cleavage is built up in accordance with good construction principles, absence of a catalyst, by heating to 60. Furthermore, any equipment and Veretwa drive 350 to 700 ⁰ C. for a residence time of 1 for the separation of ethylbenzene from the Ausbis 30 seconds at a pressure between 7.03 and used running the cracking zone. In general, 352 kg / cm * in the presence of 1 to 40 moles of water, the ethylbenzene and the benzene and the substance per mole of Dibenzyi are carried out. Dibenzyi from the An embodiment of the wehere erfindungsge- 65 \ uslauf the nip zone by conventional fractional MAESSEN method is characterized in that distillation separated. The dibenzyi that does not react at least to the dibenzyi fed to the dissociation zone can be fed back to the dissociation zone partly in a hydrocarbon, preferably in a hydrocarbon.