CATALYTIC REFORMING

CONTENTS• INTRODUCTION• FEED STOCK• REACTIONS• PROCESS VARIABLES• REFORMING CATALYST• CATALYST CHEMISTRY• VARIOUS CATALYTIC REFORMING PROCESSES• CLASSIFICATION OF C.R PROCESSES• UOP PLATFORMING PROCESS• CATALYST REGENERATION• REACTOR DESIGN• Conclusion• Q & A

INTRODUCTION• Demand of high-octane gasoline.• 30-40 % of gasoline production is by C.R.• The production might decrease by the

implementation on the aromatic content of gasoline.

• Only change in molecular structure so B.P of the feedstock after the process is small.

• C.R increases the octane of motor gasoline rather than increasing its yield. (in fact due to cracking there is a decrease in yield).

FEED STOCK• Feed consists of Heavy straight run gasoline (HSR)

Naphtha Heavy hydrocracker naphtha

• Naphtha containing (C6-C11) chain paraffins, olefins, naphthenes & aromatics.

• Aromatics in feed remains unchanged

COMPOSITION OF FEED STOCK

Major hydrocarbon groups (PONA)

Paraffin

Naphthenes

AromaticsOlefin

PONA ANALYSIS (VOL%)

FEED PRODUCT

Paraffins 30-70 30-50

Olefins 0-2 0-2

Naphthenes 20-60 0-3

Aromatics 7-20 45-60

Basics of Catalytic Reforming

•Catalytic reforming uses catalytic reactions to process primarily low octane heavy straight run (from the crude distillation unit) gasoline and naphtha into high octane aromatics (including benzene).

•Major types of reactions which occur during reforming processes : 1) dehydrogenation of naphthenes to aromatics; 2) dehydrocyclization of paffins to aromatics; 3) isomerization; and 4) hydrocracking.

•Feedstocks to catalytic reforming processes are usually hydrotreated first to remove sulfur, nitrogen and metallic contaminants.

•In continuous reforming processes, catalysts can be regenerated one reactor at a time, once or twice per day; without disrupting the operation of the unit.

REACTIONS4 major reactions are categorized as

• Dehydrogenation of naphthenes to aromatics

• Dehydocyclization of paraffins to aromatics • Isomerization

• Hydrocracking

Undesirable

Desirable

Dehydrogenation & Dehydrocyclization• Highly endothermic• Cause decrease in

temperatures• Highest reaction rates• Aromatics formed

have high B.P so end point of gasoline rises

Favourable conditions• High temperature• Low pressure• Low space velocity• Low H2/HC ratio

+ H2

n-C7H16 + H2

Isomerization• Branched isomers

increase octane rating

• Small heat effect• Fairly rapid reactions

Favourable conditions• High temperature• Low pressure• Low space velocity• H2/HC ratio no

significant effect

+ H2

Hydrocracking• Exothermic reactions• Slow reactions• Consume hydrogen• Produce light gases• Lead to coking• Causes are high

paraffin conc feed

Favourable conditions• High temperature• High pressure• Low space velocity

+

PROCESS VARIABLES

• Chosen to meet refiners yield, activity and stability need

• Primary control of changing conditions or qualities in reactor. • High temp increase octane rating but decrease run length. • High temp reduce catalyst stability but may be increased for

declining catalyst activity. Measured in WAIT or WABT.

• Pressure effects the reformer yield & catalyst stability. • Low pressure increases yield & octane but also increases coke

make.• Low pressure decreases the temperature requirement for the given

product quality

Catalyst type

Temperature

Pressure

PROCESS VARIABLES

• Amount of Naphtha processed over a given amount of catalyst.

• Low space velocity favors aromatic formation but also promote cracking.

• Higher space velocity allows less reaction time.

• Moles of recycle hydrogen / mole of naphtha charge

• Recycle H2 plays a sweeping effect on the catalyst surface supplying catalyst with readily available hydrogen

• Increase H2 partial pressure or increasing the ratio suppresses coke formation but promotes hydrocracking.

Space velocity

H2 / HC ratio

Catalytic reforming (Axens)

Application: Upgrade various types of naphtha to produce high-octane reformate, BTX and LPG.

Description: Two different designs are offered. One design is conventional where the catalyst is regenerated in place at the end of each cycle.

Operating normally in a pressure range of 12 to 25 kg /cm2 (170 to 350 psig) and with low pressure drop in the hydrogen loop, the product is 90 to 100 RONC.

With its higher selectivity, trimetallic catalysts RG582 and RG682 make an excellent catalyst replacement for semi-regenerative reformers.

The second, the advanced Octanizing process, uses continuous catalyst regeneration allowing operating pressures as low as 3.5 kg /cm2 (50 psig).

This is made possible by smooth-flowing moving bed reactors (1–3) which use a highly stable and selective catalyst suitable for continuous regeneration (4).

Main features of Axens’ regenerative technology are:

Side-by-side reactor arrangement, which is very easy to erect and consequently leads to low investment cost.

The Regen C2 catalyst regeneration system featuring the dry burn loop, completely restores the catalyst activity while maintaining its specific area for more than 600 cycles.

Finally, with the new CR401 (gasoline mode) and AR501 (aromatics production) catalysts specifically developed for ultra-low operating pressure and the very effective catalyst regeneration system, refiners operating Octanizing or Aromizing processes can obtain the highest hydrogen, C5+ and aromatics yields over the entire catalyst life.

Installation: Of 111 units licensed, 64 units are designed with continuous regeneration technology capability.

Reference: “Continuing Innovation In Cat Reforming,” NPRA Annual Meeting, March 15 –17, 1998, San Antonio.

“Fixed Bed Reformer Revamp Solutions for Gasoline Pool Improvement,” Petroleum Technology Quarterly, Summer 2000.

“Increase reformer performance through catalytic solutions,” Seventh ERTC, November 2002, Paris.

“Squeezing the most out of fi xed-bed reactors,” Hart Show Special, NPRA 2003 Annual.

Licensor: Axens.

Catalytic reforming (Howe Baker)

Application: Increase the octane of straight-run or cracked naphtha's for gasoline production.

Products: High-octane gasoline and hydrogen-rich gas. Byproducts may be LPG, fuel gas and steam.

Description: Semi-regenerative multibed reforming over platinum or bimetallic catalysts.

Hydrogen recycled to reactors at the rate of 3 mols / mol to 7 mols /mol of feed.

Straight-run and /or cracked feeds are typically hydrotreated, but low-sulfur feeds (<10 ppm) may be reformed without hydrotreatment.

Operating conditions: 875°F to 1,000°F and 150 psig to 400 psig reactor conditions.

Yields: Depend on feed characteristics, product octane and reactor pressure.

The following yields are one example. The feed contains 51.4% paraffins, 41.5% naphthenes and 7.1% aromatics, and boils from 208°F to 375°F (ASTM D86). Product octane is 99.7 RONC and average reactor pressure is 200 psig.

Economics:

Utilities, (per bbl feed)Fuel, 103 Btu release 275Electricity, kWh 7.2Water, cooling (20°F rise), gal 216Steam produced (175 psig sat), lb 100

Licensor:CB&I Howe-Baker Process and Technology.

Catalytic reforming (UOP LLC)

Application: The CCR Platforming process is used throughout the world in the petroleum and petrochemical industries. It produces feed for an aromatics complex or a high-octane gasoline blending product and a significant amount of hydrogen.

Description: Hydrotreated naphtha feed is combined with recycle hydrogen gas and heat exchanged against reactor effluent. The combined feed is then raised to reaction temperature in the charge heater and sent to the reactor section.

Radial-flow reactors are arranged in a vertical stack.

The predominant reactions are endothermic; so an interheater is used between each reactor to reheat the charge to reaction temperature.

The effluent from the last reactor is heat exchanged against combined feed, cooled and split into vapor and liquid products in a separator.

The vapor phase is hydrogen-rich. A portion of the gas is compressed and recycled back to the reactors.

The net hydrogen-rich gas is compressed and charged together

with the separator liquid phase to the product recovery section.

This section is engineered to provide optimum performance.

Catalyst flows vertically by gravity down the reactor stack.

Over time, coke builds up on the catalyst at reaction conditions.

Partially deactivated catalyst is continually withdrawn from the bottom of the reactor stack and transferred to the CCR regenerator.

Installation: UOP commercialized the CCR Platforming process in 1971 and now has commissioned more than 180 units (more than 3.9 million bpd of capacity) with another 30 in various stages of design, construction and commissioning.

Efficiency/product quality: Commercial on stream efficiencies of more than 95% are routinely achieved in CCR Platforming units.

Licensor: UOP LLC.

REFORMING CATALYST

• Catalyst used now a days is platinum on alumina base.• For lower pressure stability is increased by combining

rhenium with platinum.• Pt serve as a catalytic site for hydrogenation and

dehydrogenation reactions• Chlorinated alumina provides acid site for isomerization,

cyclization & hydrocracking reactions.• Catalyst activity reduced by coke deposition and

chlorine loss.• As catalyst age’s activity of the catalyst decreases so

temperature is increased as to maintain the desired severity.

CATALYST CHEMISTRYProperly balanced catalyst

Cl Acid functionCracking

Dehydrogenation Dehydrocyclization

Isomerization

Metal- Pt functionDemethylation

Metal-Acid balance

VARIOUS C.R. PROCESSES• Platforming (UOP)• Powerforming (Exxon)• Ultraforming (Amoco)• Magnaforming (ARCO)• Rheniforming (Cheveron)

Classification of processes

Continuous Semi Regenerative Cyclic

CATAYST REGENERATION

• Performance of the catalyst decreases wrt time due to deactivation.

• Reasons for deactivation Coke formation

Contamination on active sites

Agglomeration

Catalyst poisoning

• Activity could be restored if deactivation occurred because of coke formation or temporary poisons.

CATAYST REGENERATION

• Objective of regeneration

Surface area should be high

Metal Pt should be highly dispersed

Acidity must be at a proper level• Regeneration changes by the severity of the

operating conditions• Coke formation can be offset for a time by

increasing reaction temperatures.

CONCLUSIONS• Purpose of reforming process is to improve RONC.• The basic and fastest reaction is naphthene

conversion to aromatic so the feed rich in naphthene that is rich naphtha is preferred as a feed.

• Useful operating condition is at low pressure, low space velocity & high temperatures.

• The platinum is thought to serve as a catalytic site for hydrogenation & dehydrogenation reactions

• While chlorinated alumina as an acid site for isomerization & hydrocracking reactions.

• The activity of the catalyst decreases during the on stream period hence leading to regeneration.