Oil & Natural Gas Projects
Exploration and Production Technologies
Development of a Solid Catalyst Alkylation Process Using Supercritical Fluid
This project was funded through DOE's Natural Gas and Oil Technology Partnership
Program. The program establishes alliances that combine the resources and experience
of the nation's petroleum industry with the capabilities of the national laboratories
to expedite research, development, and demonstration of advanced technologies
for improved natural gas and oil recovery.
The goal was to develop an economical solid catalyst alkylation process via
supercritical fluid (SCF) regeneration.
Idaho National Engineering and Environmental Laboratory (INEEL)
Idaho Falls, ID
Phillips Petroleum Company (ConocoPhillips)
During experiments, alkene conversion was maintained above 90% and product quality
remained relatively constant during the entire run. Catalyst activity, based
on total product yield, was maintained above 90% of its initial level for 132
hours, representing a 15-fold increase in catalyst longevity. These preliminary
results are highly encouraging, and it is expected that significant improvements
in catalyst life and product yield and quality can be achieved as the process
is improved and optimized for commercial feeds.
This project developed an economical solid catalyst alkylation process via SCF
regeneration. Experimental data were obtained to determine the maximum number
of regenerations, minimum pressure and energy requirements, minimum SCF usage
requirements, potential for SCF recycle and reuse, and reactor design requirements
for continuous reaction and regeneration.
Alkylation is used by the petroleum refining industry to produce a low-vapor-pressure,
high-octane gasoline blendstock. Alkylate is an ultraclean-fuel component and
the cleanest gasoline blend stream produced in a refinery. Current industrial
alkylation processes catalyze the reaction with concentrated liquid mineral
acids, either hydrofluoric (HF) or sulfuric (H2SO4) acids, which pose serious
safety and environmental risks. These risks have led Federal and local governments
to cease issuing permits for construction of new HF alkylation plants.
Production of this ultraclean fuel is thus at risk and its growth severely
limited unless a replacement process can be developed. In order for alkylate
to be used as a high-volume, ultraclean fuel, an alternative safe and environmentally
acceptable alkylation process is required. Solid acid catalysts could replace
liquid acids and eliminate many safety and environmental concerns, but they
deactivate rapidly due to deposition and buildup of heavy hydrocarbons on the
catalyst surface. Typical catalyst regeneration processes are oxidative and
destroy significant levels of acidic alkylation catalyst activity. This results
in high levels of catalyst consumption, making solid catalytic alkylation economically
and environmentally unacceptable. This project is designed to develop an economical
solid catalyst alkylation process via SCF regeneration. Experimental data are
to be obtained to determine the maximum number of regenerations, minimum pressure
and energy requirements, minimum SCF usage requirements, potential for SCF recycle
and reuse, and reactor design requirements for continuous reaction and regeneration.
An automated bench scale reaction/regeneration system was reassembled. The system
is based on the use of two reactors that are alternately switched between the
reaction mix feed stream and the SCF regeneration stream. In this configuration,
one reactor is always catalyzing the alkylation reaction, while the other is
being regenerated by the SCF. The system can accommodate up to 10 grams (g)
of catalyst per reactor. The system uses automated high-pressure pumps, switching
valves, and temperature and pressure controllers. A computer-based data acquisition
and control system is used to automatically switch the reactors from reaction
to regeneration conditions. To date, the system has provided unattended experimental
runs in excess of 200 hours.
Experimental results using a model alkene feed (2-butene) have demonstrated
that a USY zeolite catalyst could be maintained at greater than 90% of initial
activity for at least 210 hours. This represented a 20-fold increase in catalyst
longevity. This result was obtained at an olefin weight hour space velocity
(OWHSV) of 0.2 g olefin/g catalyst/hour and an isoparaffin to olefin (iP:O)
ratio of 20:1. The 210 hour experiment duration does not represent a limit for
the SCF regeneration technology since the experiment was prematurely terminated
due to infrastructure difficulties. Under the set of conditions explored, each
batch of catalyst was run and regenerated 35 times.
The SCF regeneration technology was tested using a commercial alkylation feed
stream obtained from Phillips Petroleum Company (now ConocoPhillips). The feed
stream had minimal pretreatment. The olefin stream had been caustic-washed and
dried to remove mercaptans. The olefin stream contained a mix of propenes (28
wt %), butenes (68 wt %) and pentenes (4 wt %). Impurities known to deactivate
solid acid catalysts included butadiene (2,000 ppm), acetone (140 ppm), and
sulfur (16 ppm). Experiments were run at an OWHSV of 0.2 g olefin/g catalyst/hour
and a molar iP:O ratio of 19:1. Without SCF regeneration, alkene conversion
dropped below 90% after only 9 hours online. Product quality declined rapidly
after 10 hours, with cracking (C5) and oligomerization (C9+) products becoming
very significant. The SCF regeneration technology was explored using the commercial
alkylation feed, without optimization of regeneration conditions. The reaction/regeneration
experiment was run for about 200 hours.
Current Status (October 2005)
This project is complete.
Project Start: April 12, 2001
Project End: April 11, 2004
Anticipated DOE Contribution: $330,000
Performer Contribution: $0
NETL - Kathleen Stirling (firstname.lastname@example.org or 918/ 699-2008)
INL - Daniel Ginosar (Daniel.Ginosar@inl.gov or 208-526-9049)
Schematic of the automated experimental system for continuous reaction and regeneration.
Graph of Butene Conversion
Graph of Activity Recovery
Continuous solid catalyst alkylation reaction/regeneration experiment results
showing (top) butene conversion and catalyst activity recovery.