A modified process for aromatizing aliphatic feedstock to a principally aromatic containing liquid product and a principally light paraffin containing gas product which includes utilizing a two stage catalyst system in which the first stage is a ZSM-5 type synthetic aluminosilicate molecular sieve zeolite catalyst and the second stage is a mixture of such a ZSM-5 catalyst and a second molecular sieve (pore size about 4.5 to 6.7A) catalyst. The instant specification discloses a unique result flowing from this particular combination which is not achieved by either ZSM-5 or such second sieve alone, or by ZSM-5 mixed with such second sieve or with ZSM-5 followed by such second sieve; that is there is caused to be produced a liquid product having extremely small or no concentrations of C.sub.5 + aliphatics admixed with the aromatics content thereof. In a preferred embodiment hydrogen is added to the second stage catalyst zone whereby causing the gas product produced to be predominantly LPG.
A combination process for the conversion of C.sub.2 -C.sub.6 aliphatic hydrocarbons into easily transportable hydrocarbons of greater molecular weight. The combination process comprises converting the C.sub.2 -C.sub.6 aliphatic hydrocarbons to aromatic hydrocarbons in a dehydrocyclodimerization reaction zone after which the aromatic is directly hydrogenated in the presence of hydrogen from the dehydrocyclodimerization reaction step to produce large transportable aliphatic hydrocarbons. It is also an aspect of the invention that the hot hydrogenation reaction zone product stream is used to preheat the feed stream to the dehydrocyclodimerization reaction zone.
A multiple-stage catalytic conversion system in which a hydrocarbonaceous charge stock is reacted in a plurality of catalytic reaction zones, through all of which the catalyst particles flow downwardly via gravity-flow. The charge stock, in the absence of added, or recycle hydrogen, is reacted in a first reaction zone (1) into which fresh, or regenerated catalyst particles are introduced and, (2) from which deactivated catalyst particles are withdrawn for regeneration. The reaction product effluent emanating from the first reaction zone is further reacted in a multiple-zone stacked reaction system (1) into the uppermost zone of which fresh, or regenerated catalyst particles are introduced and (2) from the lowermost zone of which deactivated catalyst particles are withdrawn for regeneration. The product effluent from the lowermost reaction zone in the stacked system is separated to recover the intended product.
A combination process for the conversion of C.sub.2 -C.sub.6 aliphatic hydrocarbons into easily transportable hydrocarbons of greater molecular weight. The combination process comprises converting the C.sub.2 -C.sub.6 aliphatic hydrocarbons to aromatic hydrocarbons in a dehydrocyclodimerization reaction zone after which the aromatic product is isomerized in the presence of hydrogen from the dehydrocyclodimerization reaction step to produce transportable aliphatic hydrocarbons.
A multiple-stage catalytic conversion system in which a hydrocarbonaceous charge stock is reacted in a plurality of stacked catalytic reaction zones through which catalyst particles flow downwardly via gravity-flow. The charge stock, in the absence of added, or recycle hydrogen, is reacted first in the lowermost reaction zone, from which deactivated catalyst particles are withdrawn from the system. Resulting reaction zone effluent is further reacted in the uppermost reaction zone, through which fresh, or regenerated catalyst particles are introduced into the system, and serially in one or more subsequent, lower reaction zones. Product effluent from the reaction zone immediately above the lowermost zone is separated to recover the desired normally liquid product.
The present invention relates to a process for producing aromatic compounds from C.sub.2 -C.sub.6 aliphatic hydrocarbons. In this process, a feedstock containing C.sub.2 -C.sub.6 aliphatic hydrocarbons is passed into a reaction zone and into contact with a catalyst zone containing two discrete catalysts. The first catalyst of the discrete catalyst system is comprised in part of a ZSM-5 zeolite component while the second catalyst of the discrete catalyst system is comprised in part of a catalytically active component that is not ZSM-5 which exhibits an acidity lower than that of the first discrete catalyst. A metallic component selected from the Group IIB to IVB Elements of the Periodic Table may be a component of one or both of the discrete catalysts of the instant process as can be a phosphorus-containing alumina component. The discrete catalytic system of the present invention is particularly suited for selectively producing aromatic compounds from C.sub.2 -C.sub.6 aliphatic hydrocarbons while limiting the amount of undesired C.sub.1 and C.sub.2 by-products produced by the process.
