Robert J. Taylor

Selective hydroisomerization of long chain normal paraffins

Abstract The removal of long chain normal paraffins from lubricating oils is essential to produce an oil with acceptable cold flow properties. Conventional lubricant dewaxing processes remove these normal paraffins by selective cracking or crystallization mechanisms, resulting in a yield loss directly proportional to the concentration of the normal paraffins in the oil. More recent lubricant dewaxing processes attempt to isomerize the normal paraffins to isoparaffins, allowing them to remain in the oil and produce a higher quality oil in higher yield. The work reported here is a study of the effect of zeolite type and acidity on the selective isomerization of the long chain normal paraffins typically found in lubricating oils. Catalysts containing beta, USY, SDUSY, mordenite, ZSM-5 and SAPO-11 are tested for their ability to isomerize neat hexadecane and a 50:50 mixture of hexadecane and tetramethylpentadecane. Beta, SAPO-11 and ZSM-5 are also tested with a refined wax distillate lubricating oil which contains 15% normal paraffins. In summary, these results show that SAPO-11 was the only catalyst tested which was capable of isomerizing normal paraffins in the presence of isoparaffins without large yield losses due to unwanted cracking.

Effects of process parameters on isobutane/2-butene alkylation using a solid acid catalyst

Abstract Alkylation processes based on solid acid catalysts have been studied with varying degrees of urgency for the last three decades. Work has focused on developing both catalysts and processes. Unfortunately, much of the catalyst development work was done under conditions where catalyst deactivation was rapid and possibly accelerated by the test equipment chosen to compare catalysts and conditions. Under these circumstances, the true performance of the catalyst for alkylation was not measured. This paper reports a study of the effect of time-on-stream, olefin concentration, feed olefin residence time, temperature, and catalyst loading for isobutane/2-butene alkylation using a continuous stirred reactor (CSR) system. A CSR system has been shown to give relatively constant activity over much greater times than conventional fixed-bed or batch reactor systems. The effects of these parameters on olefin conversion, useful catalyst lifetime and product quality are reported and initial rate constants, catalyst deactivation rates and an energy of activation for olefin conversion are calculated. In summary, these experiments show the dramatic effect of time-onstream for the reaction of isobutane and 2-butene, which exhibits four distinct stages of activity and selectivity. The first stage is the “initial activity”, which is never actually observed due to experimental limitations but is important in kinetic treatment of the data. The second stage is the “useful lifetime of the catalyst”, which is characterized by high olefin conversion and relatively slow catalyst deactivation. The third stage is the “rapid deactivation” region where a rapid loss of catalyst activity for olefin conversion coupled with a change in selectivity from C 5 –C 8 products to C 9+ products occurs. The fourth stage is where the product of olefin conversion is primarily C 9+ products and the deactivation is again rather slow. These experiments also show that most changes in experimental conditions which increase the concentration of unreacted olefin (e.g., decreasing olefin conversion by increasing feed olefin concentration, decreasing feed olefin residence time, etc.) decreases the catalyst lifetime and product quality. The experiments also show that there is an optimum reaction temperature which balances the low olefin conversion at low temperature and the high oligomerization activity at high temperature. A set of performance equations from kinetic parameters were derived to describe the conversion of 2-butene under various experimental conditions using a USY catalyst. These performance equations allowed the calculation of initial conversion activity, change in conversion activity over time and an estimate of the useful lifetime of the catalyst.

Diisopropyl ether one-step generation from acetone-rich feedstocks

A one-step integrated process for the generation of the high-octane fuel ether, diisopropyl ether (DIPE), from acetone-rich feedstocks has been demonstrated. Three continuous, downflow, reactor configurations have been considered, including a two-bed catalyst design separated by inerts, gradient multicatalyst combinations, and an integrated two-zone layout with differing catalyst compositions. The bifunctional catalysts have both hydrogenation and etherification/dehydration capabilities and may comprise groups IB, VIB, and VIII metals incorporated into acidic, large and medium-pore zeolites, groups III or IV metal oxides, as well as heteropoly acid structures. DIPE syntheses are typically conducted at 100–165°C, under hydrogen pressure. The gradient reactor design, with careful choice of hydrogenation and etherification catalysts, allows DIPE to be generated in high selectivity and productivity.