GB881892A - Emulsion modification in alkylation catalyst separation - Google Patents

Abstract

<PICT:0881892/IV (b)/1> <PICT:0881892/IV (b)/2> <PICT:0881892/IV (b)/3> In the alkylation of an isoparaffin with an olefin employing a liquid acid catalyst emulsified with the reactants by the process of Specification 804,966 in which the emulsion is modified prior to settling by increasing the hydrocarbon content, unbroken emulsion is continuously removed from the settling zone from the layer between the separated hydrocarbon and acid layers and recycled to the emulsion modifying zone or to a zone of relatively high acid content, e.g. the final alkylation stage or the inlet to the emulsion modifying zone. The settling apparatus (Fig. 2) is similar to that in Specification 804,966 with the addition of conduit 78 for withdrawal of unbroken emulsion. Automatic control of the withdrawal of acid and emulsion may be provided by floats (Fig. 8) 80 floating on the emulsion and 81 floating on the acid, a constricted by-pass line 87 being provided round emulsion withdrawal valve 85 so that withdrawal of emulsion is never completely cut off. Other means of control may be used such as a conductivity cell, radioactive probe or a level differential control of the external displacement type. A modified settler is shown in Fig. 9 in which the emulsion breaking zone is bounded by a cylindrical baffle 60 containing inclined baffles 151. Hydrocarbon flows over the top of baffle 60 to the modifying zone and the final settling zone, acid is removed by conduit 65 and unbroken emulsion by conduit 178. Due to the greater height obtainable the length can be decreased and the region of unbroken emulsion is more clearly defined.