119
Y. However, it offers a challenge in its adoption for alkylation process
development due to the exothermic nature of the reaction, which in turn demands
rapid cooling of regenerated catalyst to meet desired low to moderate temperature in the reaction zone.
2. Solvent extraction: This concept employs solvent to extract hydrocarbon deposits from the spent catalyst but has limitations in extracting coke. In the alkylation
process, solvents like isobutane and supercritical solvents have been tested for
their effectiveness, but they all lead to only partial restoration of the activity.
3. In situ regeneration in the presence of hydrogen: Hydrogen is also widely used
in the regeneration of solid acid catalysts. The treatment is carried out at reaction
as well as elevated temperatures. The catalyst is typically loaded with a hydrogenation function, for example, a nobel metal. The regeneration takes place through
two mechanisms depending on the temperatures used. Hydrogenation of highly
unsaturated species, which block the acid sites and not the pores, takes place at
temperatures below 373 K. At higher temperatures, hydrocracking of the bulky
long-chain alkanes, which block the pores, occurs, resulting in the regeneration
of the catalyst.
Considering these facts, solid acid alkylation processes are developed as per
details given below:
CB&I, Albemarle Corp., and Neste Corp. AlkyClean™ Process
The world’s first commercial-scale, solid acid catalyst-based alkylation unit with a
capacity of 2700 barrels per day of alkylate production (100,000 tpy), based on the
AlkyClean technology jointly developed by CB&I, Albemarle Corp., and Neste
Corp., has been put on stream in 2015 at Zibo Haiyi Fine Chemical Co. Ltd., China
[115]. The AlkyClean technology uses Pt/US-Y, a fixed-bed zeolite developed by
Albemarle with the trade name of AlkyStar. The temperature of the operation is
323–363 K, and the isobutane/alkene feed ratio is kept between 8 and 10 [116].
There are no stringent requirements for feed treatment as the catalyst is robust and
insensitive to feed impurities. A high-quality alkylate product is produced by the
AlkyClean process using the novel reactor scheme of CB&I, without the use of
conventional liquid acid catalysts typical of conventional alkylation technologies,
thus making the process inherently safer and cost effective. With the elimination of
downstream treatment of waste streams such as acid soluble oils, the AlkyClean
process is an efficient technology for the production of alkylate compared to mineral acid-based process. The process utilizes a series of reactors with distributed
injection of olefin feed to achieve high isobutane/alkene ratios internally. It is
claimed that the reactor configuration reduces the alkene gradients across the reactor by achieving a high degree of mixing. Thus, the process operates with multiple
reactors, which alternate between reaction and regeneration mode of operations.
The regeneration is performed at reaction temperature and at an elevated temperature of 523 K. In both cases, the regeneration is carried out in the hydrogen
Emerging Trends in Solid Acid Catalyst Alkylation Processes
Y. However, it offers a challenge in its adoption for alkylation process
development due to the exothermic nature of the reaction, which in turn demands
rapid cooling of regenerated catalyst to meet desired low to moderate temperature in the reaction zone.
2. Solvent extraction: This concept employs solvent to extract hydrocarbon deposits from the spent catalyst but has limitations in extracting coke. In the alkylation
process, solvents like isobutane and supercritical solvents have been tested for
their effectiveness, but they all lead to only partial restoration of the activity.
3. In situ regeneration in the presence of hydrogen: Hydrogen is also widely used
in the regeneration of solid acid catalysts. The treatment is carried out at reaction
as well as elevated temperatures. The catalyst is typically loaded with a hydrogenation function, for example, a nobel metal. The regeneration takes place through
two mechanisms depending on the temperatures used. Hydrogenation of highly
unsaturated species, which block the acid sites and not the pores, takes place at
temperatures below 373 K. At higher temperatures, hydrocracking of the bulky
long-chain alkanes, which block the pores, occurs, resulting in the regeneration
of the catalyst.
Considering these facts, solid acid alkylation processes are developed as per
details given below:
CB&I, Albemarle Corp., and Neste Corp. AlkyClean™ Process
The world’s first commercial-scale, solid acid catalyst-based alkylation unit with a
capacity of 2700 barrels per day of alkylate production (100,000 tpy), based on the
AlkyClean technology jointly developed by CB&I, Albemarle Corp., and Neste
Corp., has been put on stream in 2015 at Zibo Haiyi Fine Chemical Co. Ltd., China
[115]. The AlkyClean technology uses Pt/US-Y, a fixed-bed zeolite developed by
Albemarle with the trade name of AlkyStar. The temperature of the operation is
323–363 K, and the isobutane/alkene feed ratio is kept between 8 and 10 [116].
There are no stringent requirements for feed treatment as the catalyst is robust and
insensitive to feed impurities. A high-quality alkylate product is produced by the
AlkyClean process using the novel reactor scheme of CB&I, without the use of
conventional liquid acid catalysts typical of conventional alkylation technologies,
thus making the process inherently safer and cost effective. With the elimination of
downstream treatment of waste streams such as acid soluble oils, the AlkyClean
process is an efficient technology for the production of alkylate compared to mineral acid-based process. The process utilizes a series of reactors with distributed
injection of olefin feed to achieve high isobutane/alkene ratios internally. It is
claimed that the reactor configuration reduces the alkene gradients across the reactor by achieving a high degree of mixing. Thus, the process operates with multiple
reactors, which alternate between reaction and regeneration mode of operations.
The regeneration is performed at reaction temperature and at an elevated temperature of 523 K. In both cases, the regeneration is carried out in the hydrogen
Emerging Trends in Solid Acid Catalyst Alkylation Processes