Trond Myrstad

Sulphur reduction of fluid catalytic cracking (FCC) naphtha by an in situ Zn/Mg(Al)O FCC additive

Abstract A number of solutions for the reduction of sulphur in fluid catalytic cracking (FCC) naphtha have been suggested. One possible solution would be to use an FCC catalyst or an FCC catalyst additive which could reduce the sulphur content in the FCC naphtha in situ in the cracker itself. Through this work, it has been shown that an FCC-additive made by impregnating zinc on a hydrotalcite-like material is able to give a significant reduction of naphtha sulphur in MAT experiments, while the hydrotalcite material itself gives only a minor reduction of naphtha sulphur. It has also been shown that the additive has no effect on catalyst activity, but gives an unwanted increase in the production of coke.

Effect of nickel and vanadium on sulphur reduction of FCC naphtha

Abstract A number of solutions to reduce sulphur in fluid catalytic cracking (FCC) naphtha have been suggested. One of these is to reduce the sulphur content in the FCC reactor by using an FCC catalyst or an FCC catalyst additive. In most of the published laboratory investigations within this field, steam-deactivated, metal-free FCC catalysts have been used. This study discusses the effects of nickel and vanadium present on the FCC catalyst with respect to the sulphur level in FCC naphtha. The effects of these metals are discussed both in the absence and the presence of a sulphur-reduction additive. The study shows that the sulphur level in FCC naphtha is significantly lower when testing with metal-impregnated catalysts as in the case when testing the catalysts in the absence of metals. The study also shows that, when mixed with metal-impregnated catalysts, the effect of a sulphur-reduction additive is prohibited.

A comparison of laboratory deactivation methods for FCC catalysts

Abstract Two different methods for laboratory deactivation of FCC catalysts have been compared to deactivation in a commercial FCC unit. The two laboratory methods investigated were: (i) metals impregnation by an incipient wetness method according to Mitchell followed by steaming, and (ii) cyclic impregnation and deactivation in a cyclic deactivation unit (CDU). The cyclic deactivation method consists of cycles with cracking of metal spiked feed, stripping and regeneration in a fluidized bed reactor. An apparatus for cyclic deactivation is described. To find the better laboratory deactivation method the three deactivated catalyst samples were chemically and physically characterized and micro activity tested (MAT) with North Sea atmospheric residue as feed. It was found that cyclic deactivation gave a better simulation of the equilibrium catalyst from the FCC unit (ECAT) than was the case for Mitchell impregnation and steaming. The metals are still more active for dehydrogenation reactions following cyclic deactivation than metals are in the ECAT, although cyclic deactivation represents an improvement compared with impregnation and steaming. It was found also that fresh catalyst particles in ECAT contribute significantly to product distribution and quality, making ‘perfect’ simulation of ECAT with laboratory deactivated samples consisting of uniformly deactivated particles very difficult. Significant differences were not found in metal distribution across the catalyst particles resulting from the different deactivation procedures. It was found that vanadium migrates more easily through the catalyst particles than nickel during the deactivation.

Quantitative determination of Ni and V in FCC catalysts monitored by ESR spectroscopy

Calibration mixtures containing Ni0 and V4+ in the range from 500 to 4000 ppm have been prepared using various supports (silica, alumina, titania and ultrastable Y zeolite (USY)) with different particle sizes. ESR measurements revealed a linear relation between the impregnated metal amounts and the registered ESR signal integrals and/or intensities, suitable for the determination of the NiO (reduced to Ni0) and V4+ contents in FCC catalysts, respectively. The amount of NiO in a FCC equilibrium catalyst was determined to about 1300 ppm of a total of 2500 ppm Ni compound present in this sample, whereas the amount of V4+ was estimated to about 1800 ppm of a total of 2800 ppm vanadium species. Hence, this catalyst contains about 1000 ppm V5+.

Effect of vanadium on octane numbers in FCC-naphtha

Abstract The effect of vanadium on catalyst activity and yield in Fluid Catalytic Cracking (FCC) is well described, but very little is reported about the effect of vanadium on the octane numbers of FCC-naphtha. In this work the effect of vanadium on FCC-naphtha octane numbers was investigated by testing FCC-catalysts with and without a vanadium trap in a Micro Activity Test reactor. During this work it was confirmed that the addition of a vanadium trap to an FCC-catalyst increased the catalyst activity and naphtha yield. It was also found that when vanadium was removed from the FCC-catalyst, the naphtha octane numbers decreased. The results can be explained by increased hydrogen transfer and decreased dehydrogenation of paraffins and naphtenes. The results from this work indicate that adding a vanadium trap would increase activity and naphtha yield in a commercial FCC-unit. Octane barrels would also increase; however, the octane numbers could be reduced, dependent on the unit operation. If the FCC-unit is octane constrained, this could be a problem.

Evaluation of residue FCC catalysts

Abstract The processing of residues in FCC units has become a field of considerable interest over the past few years. The goal of our own work within this area, which has now extended over several years, has been to identify catalysts which are capable of giving improved process economy. In order to find the most suitable catalysts, and to understand why some catalysts are more suitable than others, a broad range of physical and chemical test methods have been employed. Those test methods employed by us are discussed in the current paper, exemplified by an authentic evaluation. The execution of such a test program involving a broad range of test methods is quite expensive, nevertheless it has been found to be of great value.

Test of magnetically separated catalysts in an ARCO pilot unit

Abstract Two different equilibrium catalysts from a FCC unit have been separated by the MagnaCat™ process, into fractions of different magnetic susceptibility. The results showed that the magnetic separation was influenced by gravity and inertia forces. Large particles had a tendency to accumulate in the accepted, least magnetic fraction which is to be returned to the regenerator. The results also indicated that the two equilibrium catalysts under investigation could respond somewhat differently to the magnetic separation. The equilibrium catalysts and the treated catalysts with the most magnetic fraction removed, were tested and evaluated in a modified ARCO pilot unit. The feed used was a North Sea 375°C+atmospheric residue. The evaluation showed that the catalytic activity increased, resulting in higher gasoline production at the expense of gas and coke, when the most magnetic fraction was removed. The economic evaluation showed a potential for improved cost margins for both catalysts if the benefit of the magnetic separation was used to improve catalyst activity, selectivity and throughput in the FCC unit at constant catalyst make up rate. If on the other hand the benefit of the magnetic separation was used to lower the catalyst consumption the addition of value would rise to a lesser degree.

Effect of sodium deposition of FCC catalysts deactivation

Abstract A method for evaluating the sodium tolerance of FCC catalysts by use of a cyclic deactivation unit (CDU) has been developed. In the CDU sodium is impregnated on the catalyst through the introduction of sodium naphthenates into the feedstock during the cracking step. The sodium tolerance of commercial FCC catalysts was studied using this method. Both the amount of added sodium and vanadium were varied to study the effect of increasing metal loading. The deactivated samples were characterised (nitrogen adsorption, elemental analysis, XRD) and tested in MAT. The effect of increasing amounts of sodium on the cracking behaviour of the FCC catalysts was very small compared to the effect of increasing amounts of vanadium. Sodium deposition resulted in a lower activity and less hydrogen transfer reactions, leading to more olefins and less paraffins in the gasoline product. For the commercial FCC catalysts at least 4500 ppm sodium at a level of about 2–2500 ppm vanadium could be applied without changing the cracking characteristics significantly, or without a break-down of the catalyst structure.

A study on the effect of sodium chloride deposition on an FCC catalyst in a cyclic deactivation unit

A new method for the addition of sodium to cracking catalysts in a cyclic deactivation unit (CDU) has been established. Sodium was added to a commercial residue FCC catalyst via an aqueous solution of sodium chloride prior to the cracking step in the CDU. The deactivated samples were characterised and tested in a microactivity test (MAT). The effect of sodium chloride deposition was compared with the effect of sodium naphthenate added via the cracker feed of the CDU. The results show that the addition of sodium chloride up to a level of 5000 ppm sodium give similar changes in catalyst behaviour and characteristics as when sodium naphthenate is used as the sodium source. The addition of up to 5000 ppm sodium leads to a significant decrease in the zeolite content, a certain reduction in activity and hydrogen yield, and a reduction in the extent of hydrogen transfer reactions. The results indicate that sodium chloride leads to a smaller decrease in the hydrogen transfer reactions compared to the addition of sodium naphthenate when 5000 ppm sodium is added. Sodium does not affect the gasoline octane numbers significantly.

Testing of resid FCC catalysts in MAT

Employing atmospheric residues when testing FCC catalysts in MAT often faces serious problems with poor mass balances and interrupted operation due to coking of the equipment. When changing to a feed-injection tube made by electroformed nickel (EFNI) in the Statoil MAT unit, the scattering in mass balances was reduced by a factor of four, and the number of interrupted test series was decreased by a factor of two. The reason for the improved results, using an EFNI tube, is the materials lower tendency to form coke, and consequent reduction in clogging.