AlkyClean

In 1999, Akzo Nobel (which later sold its catalyst division to Albemarle) patented a new technology for alkylating hydrocarbons based on a zeolite acid catalyst [193]. This new process, AlkyClean, was then designed by ABB Lummus and Albemarle, and a 10 barrels per stream day (BPSD) demonstration unit came online in Finland in 2002. AlkyClean produces a high-quality sulfur-free alkylate (96 octane), eliminating all the drawbacks of the liquid acid catalyst technologies. There are no add-soluble oil waste streams, the reactor operates at 50-90 °C, and the catalyst is a solid, noncorrosive material, which is easily transported and stored. 

Figure4.31 A simplified design scheme ofthe AlkyClean process, using three reactors in a cyclic configuration. At any given time, two reactors are used for alkylation, while the catalyst in the third reactor is regenerated.

Like the AVADA and the AlkyClean processes, these two processes also replace the liquid acid/base catalysts with solid acids and bases [192]. Although the reaction mechanism for the heterogeneous acid-catalyzed esterification is similar to the homogeneously catalyzed one [207,208], there is an important difference concerning the relationship between the surface hydrophobicity and the catalyst s activity. This is especially true for fatty acids, which are very lipophilic compounds. One can envisage three cases First, if there are isolated Bronsted acid sites surrounded by a... 

This chapter discusses alkylation and its evolution into a modern refining process. We review the basic chemistry of alkylation, assess the properties and other merits of H F versus H2SO4, identify key drivers in the process and discuss the evolution of one particular process - the AlkyClean solid acid catalyst alkylation process. 

AlkyClean Alkylation Process A True Solid Acid Catalyst (SAC) Process... 

The AlkyClean catalyst contains no halogens, has acid sites with sufficient strength for alkylation, yields high quality alkylate with minimal side reactions, and exhibits the required activity, stability and regenerability characteristics necessary for a successful process. It is promoted with a low Pt content to assist regeneration and hydrogen transfer. 

In commercial practice, there will be significant differences in olefin feed composition. Under the AlkyClean process cyclic operation, high RON is obtained over a prolonged time period with various feeds. The use of a refinery-sourced MTBE raffinate gave similar results (alkylate yields and product quality) to a pure cis-2-butene feed (Table 12.9). The MTBE raffinate contained about 26wt% trans-2-butene, 15 wt% cis-2-butene, 12 wt% 1-butene, 2 wt% isobutene, 40 ppmw (parts per million by weight) of various oxygenates and 3 ppmw of sulfur (balance isobutane and n-butane). 

Table 12.9 Effect ofvarious butene feeds on the AlkyClean process performance at identical process conditions [19].

Similarly, after blending about 30vol.% of propylene with cis-2-butene, the RON loss was less than 1 number. With H2SO4 alkylation, similar amounts of propylene would lead to a RON about 1.5 lower. Table 12.10 summarizes the estimated impact of feedstock variation on RON relative to a pure cis-2-butene feedstock for the AlkyClean process and liquid acid technologies. Based on these results, it can be concluded that our new SAC technology is less sensitive to feedstock variation regarding product quality than either liquid acid technology. 

In contrast, the AlkyClean solid acid catalyst contains no halogens and it is very robust with regard to water and other potential feed impurities. This was observed even after exposure of the catalyst to high concentrations of oxygenates (250-700 ppmw), sulfur compounds (200-1200 ppmw) and butadiene (400-1800 ppmw). Moreover, after any observed deactivation from these impurities, the catalyst could always be restored to full activity via HTR (i.e., treatment with H2 at 250 °C). Furthermore, in... 

Figure 12.12 Simplified block diagram of the AlkyClean process [19].

The process flow scheme for the AlkyClean process is similar to that employed for current liquid acid technologies. As illustrated in the block flow diagram in Figure 12.12, the process consists of four main sections feedstock pretreatment (optional, depending on contaminant level), reactor system, catalyst regeneration and product distillation. 

Key to the AlkyClean technology s superior performance is the coupling of a newly developed catalyst with a novel alkylation reactor system, which minimizes the peak... 

Construction of an AlkyClean process demonstration unit at Fortum s facilities in Porvoo, Finland, was completed in 2002. Figure 12.14 shows the process flow schematic of the demo unit, which contains all of the key elements of our proposed commercial design. Three reactors are included - two under cyclic operation (i.e., alternating between alkylation and mild regeneration) allowfor continuous production... 

Figure 12.15 is a photograph of the installed demo reactor section. The demo reactors are sufficiently large and proportioned to allow for reliable scale-up. As such, each demo reactor represents a core of a much larger reactor and provides for the necessary hydrodynamic similarity (e.g., equivalent superficial velocities) to a full commercial-scale reactor system. Equally important, these reactors use AlkyClean catalyst produced in commercial manufacturing trials, not developmental-scale catalyst with characteristics that may not be fully duplicable under commercial-scale production conditions. 

The AlkyClean process demonstration unit was built and operated with the following objectives ... 

Table 12.12 provides an overview of the competitiveness of the AlkyClean process versus the established liquid add technologies. The performance and economics of the... 

AlkyClean process are fully competitive tvith current liquid acid technologies. High quality product has been produced in an operation that has proven to be reliable and robust. Sensitivity to feedstock variation is lotv and tolerance to impurities is high. The economic competitiveness of the netv SAC process is enhanced by its low mechanical complexity and the use of common (i.e., non-proprietary) refinery process equipment. 

Table 12.12 Comparison of AlkyClean process with liquid acid technologies.

Parameter Modern sulfuric acid Modern HF acid AlkyClean process... 

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