Hydroisomerization of 1-Pentene to Iso-Pentane in a Single Reactor

Abstract

It has been shown that hydroisomerization of an olefinic feed to an iso-paraffinic product can be performed in a single reactor using a platinum on mordenite (Pt-MOR) zeolite catalyst. This conversion finds application in a Fischer-Tropsch refinery where the syncrude is rich in olefins and conventional hydroisomerization would require hydrogenation of the feed as a feed pretreatment step. In order to demonstrate that the proposed process configuration is viable from a catalysis point of view, the hydroisomerization of 1-pentene over Pt-MOR has been investigated experimentally in the range 200 -270 C, 2 MPa, WHSV 1-3 h À1 , and H 2 :1-pentene molar ratio of 3:1-5:1. The catalyst was stable during one week of continuous operation. The highest iso-pentane yield (69%) was obtained at 250 C. Side reactions (dimerization and cracking) increased with increasing temperature, decreasing H 2 :1-pentene ratio, and increasing space velocity.

Refining Technology Selection

“…Some metals are efficient for partial HYD and double bond isomerization [33]. In some cases, the heat of alkene HYD can be exploited while controlling the alkene partial pressure and avoiding catalyst deactivation by thoughtful design [37]. When double bond isomerization takes place with partial HYD, it is not only beneficial for downstream processing but also serves as an upgrading step (Section 16.4.1).…”

“…It has also been shown that hydroisomerization technology can be employed without pretreatment with straight-run Fischer-Tropsch naphtha that is rich in n-alkenes [37]. 2) Hydroisomerization of C 5 -C 6 naphtha produces a good quality paraffinic motor-gasoline blending component.…”

Isomerization

“…2) Recycle operation during naphtha hydroisomerization allows the production of a better quality isomerate. When straight-run syncrude is fed directly to a Pt/MOR hydroisomerization process, the heat of alkene hydrogenation can be utilized to lower the fresh feed preheater temperature from 260 to 100-150 • C ( Figure 18.5) [34]. All material can be isomerized, and the actual equilibrium conversion affects only the size of the recycle stream.…”

Motor‐Gasoline Refining

“…The design intent of placing the C 5 separation before the hydrotreater was to beneficially use the heat of alkene hydrogenation in the C 5 hydroisomerization unit [18]. By implication, a Pt/MOR catalyst must be selected (Section 18.3.2).…”