Vulcan Series Chloride Removal Technology VGP CRT 2000 and ...

GBH Enterprises Ltd. 

Catalysts, Process Technology Consultancy 

Sales and Service 

Vulcan Series Chloride Removal Technology 

VGP CRT 2000 and VGP CRT 3000 

For Low and High Temperature Chloride Removal 

From Hydrocarbon Gases and Liquids 

From Catalytic Reformer Product Streams 

By: 

Gerard B. Hawkins 

Managing Director 

Date: 28, April, 2008 

Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown 

Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass 

Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance 

Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / 

Process Technology - Ammonia Catalyst / Process Technology - Methanol Catalysts / process Technology – Petrochemicals 

Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries 

Web Site: www.GBHEnterprises.com

CONTENTS 

1. Dechlorination: Commercial Applications 

2. VGP CRT 2000 / 3000: Chemical & Physical Properties 

3. Key Benefits 

4. Removal of Chlorides From Catalytic Reformer Product 

Streams. 

4.1 Introduction 

4.2 Alumina as a chloride guard 

4.3 HCl Removal Method 

4.4 By Product Formation 

5. "FAQ" Frequently Asked Questions 

6. Performance Monitoring: 

7. Flow Direction 

8. Process Gas Pressure 

9. Process Gas Temperature 

10. Re-contactor / Separation Drum 

11. VGP CRT 2000 & 3000: Analytical Procedures 








1.0 Dechlorination: Commercial Applications 

Third generation high capacity high activity VGP CRT 2000 / 3000, has been developed 

to significantly improve the cost efficiency of Dechlorination in terms of $ per Lb. of 

chloride removed, compared to conventional activated and promoted alumina based 

absorbents, opposite the following applications: 

Purification (Dechlorination) of the gaseous process effluent streams associated 

with Catalytic Reforming: 

Net Gas Make (H 2 ). 

Stabilizer column Offgas, Light Ends to Recovery Gas Make, 

LPG 








VGP CRT Series Chloride (Halogen) Removal Catalysts 

Reaction Principle: 

2HCl + MO=MCl 2 +H 2 O 

Chemical and Physical Properties: 

Chemical Composition: CRT 2000 CRT 3000 

% CaO ca 40 > 20 

% Na 2 O ca 30 > 10 

% ZnO ------ > 20 

SiO 2 > 6.5 > 6.5 

% Al 2 O 3 > 1.5 > 1.5 

Physical Properties: 

Appearance Black Grey 

Form: Extrudate Extrudate 

Size, mm Size Φ3.5mm x 4-15mm 

Bulk Density, kg/l 0.60~0.80 0.60~0.80 

Crushing Strength, N/cm ≥50 ≥50 

HCl Working Capacity, % ≥20 ≥ 25 

HCl Outlet, ppm ≤0.01 ≤0.01 








3.0 Key Benefits - 

Chloride removal from hydrocarbon gases. 

Quantitative Chloride Removal - Twenty five plus percent (25 + %) chloride 

loading. 

NO CO 2 Evolution 

Non Hazardous Classification of the Spent Absorbent. A key competitive advantage of 

VGP CRT 2000 / 3000 is that it contains no acidic surface sites, eliminating the need to 

neutralize VGP CRT 2000 / 3000 after discharge from the reactor. 

It is safe for handling and suitable for landfill in locations where this is possible. 

- Minimal benzene adsorption. 

- Minimal leachable "surface" acidity. 

Minimal surface acidity also prevents undesirable side reactions that affect alumina 

because of its acidic nature, i.e., condensation/polymerization reactions resulting in 

minimal organic chloride formation, no green oil formation or poly-cyclic aromatic fouling 

of the bed and downstream equipment. 

Resistance to C6+ (high molecular weight components) surface fouling from either direct 

condensation or synthesis across the surface. 

Recovery from liquid hydrocarbon wetting. VGP CRT 2000 / 3000 will recover from 

reformate or light ends impingement / condensation as long as it is appropriately dried 

out. 

Performance independent of the moisture content of the hydrocarbon stream. 

VGP CRT 2000 / 3000 should not be plugged by ammonium chloride solids. 

In summary, our chloride absorbent VGP CRT 2000 / 3000 offers the following benefits: 

- Unique structure and composition which removes chlorides by chemical reaction 

rather than by chemisorption as is the case with other competitive products on 

the market. 

- High capacity for chlorides (> 25 % W/W) which means longer bed life on your 

plant and lower operating costs per year. 

- The spent material is totally recyclable. 

- No formation of byproducts such as organic chlorides or green oils during its 

operating life. 








4.0 REMOVAL OF CHLORIDES FROM CATALYTIC REFORMER PRODUCT STREAMS 

4.1 Introduction 

Traditionally chlorides have been removed from catalytic reformer products streams 

using fixed beds of adsorbents. For many years alumina has been used as the 

adsorbent. Alumina offered a reasonable capacity for chlorides and was sold at low 

commodity prices. 

In recent years alumina users have become more aware of its limitations and its 

popularity has decreased. The main reasons why alumina limitations have become more 

apparent in recent years: 

- Analytical techniques have become better and are able to detect slip of chlorides from the 

alumina beds. 

- Recognition that, alumina beds promote the synthesis of organic chlorides which slip 

from the bed. 

- Higher severity operations (such as CCR and cyclic style units) are more common and 

the problems with alumina are particularly noticeable on these units 

- Increasing regulations on disposal of spent catalysts has caused problems for users of 

alumina. 

4.2 Alumina as a chloride guard 

To appreciate the limitations of alumina it is first necessary to understand how alumina 

removes chlorides. The alumina surface is covered with active sites, which are either 

negatively charged hydroxyl groups or positively charged aluminum sites. These polar 

sites are capable of attracting polar molecules, and the more polar the molecule the 

greater the attraction. 

Hydrogen chloride is quite polar (dipole moment of 1.08 Debyes) and will be adsorbed to 

the surface of the alumina. For the more active sites on the alumina there may even be 

some disassociation of the hydrogen chloride with the negatively charged chloride 

aligning with the aluminum sites and the positively charged hydrogen ion being released 

from the surface. However, most of the hydrogen chloride is not disassociated. 

Thus most of the hydrogen chloride is removed by physical adsorption on the surface 

(rather than by chemisorption where there is actually a rearrangement of the electron 

structure between the surface and adsorbing molecule-taking place). The physisorbed 

intermolecular forces are weak and sensitive to changes in the operating environment. 

The actual concentration of hydrogen chloride at the surface of the alumina is determined 

by equilibrium with the hydrogen chloride partial pressure in the gas. This equilibrium 

constant is sensitive to changes in: 








- HCl concentration:Langmuir isotherms show that the loading of hydrogen chloride on 

the alumina surface is a function of the hydrogen chloride partial pressure. 

- Operating pressure:because this affects the HCl partial pressure 

- Temperature:adsorption is exothermic and increasing temperature decreases the 

amount of adsorbed HCl 

- Water concentration:reasonable quantities of water (0.1 %) are necessary to achieve 

a reasonable degree of chloride loading on the alumina 

4.3 HCl REMOVAL METHOD 

There are three ways in which HCl can be removed from a gas stream by use of a fixed 

granular bed. These are: 

i) - Chemical Reaction (Reactive Adsorption) 

ii) - Chemisorption 

iii) - Transformation 

VGP CRT 2000 & 3000 removes hydrogen chloride by a non-reversible chemical 

reaction between HCl and the catalyst itself to form a neutral salt product, which remains 

as part of the catalyst particle. At no time is there free HCl remaining on the surface of 

the VGP CRT SERIES catalyst. This mechanism of chemical absorption is simple. An 

HCl molecule hits the catalyst surface, forms transitional chloride complexes and 

ultimately reacts with the mixed metal oxides inside the catalyst. 

Activated aluminas remove HCl primarily via adsorption. The hydrogen chloride molecule 

has a high dipole moment and is attracted to the polar sites on the alumina surface where 

it is chemisorbed (partially dissociated). The saturation (equilibrium) amount of HCl 

chemisorbed is determined by the partial pressure of HCl, the water content of the carrier 

gas and the number of active adsorption sites on the alumina surface. There is some 

evidence to suggest that the partially dissociated chloride forms stronger bonds with the 

alumina surface than can be attributed simply to adsorption. The rate of formation of 

these bonds is low and is noticeable in beds, which have been on service for a few years. 

In these cases hot purging cannot strip the HCl. The presence of water will nevertheless 

liberate HCl from the alumina. Within shorter periods of time there is little or no reaction 

of the HCl with the alumina and the chemisorbed HCl molecules remain as a surface 

layer on the alumina. Thus their chemisorption is reversible by hot purging. 

Promoted aluminas contain a small quantity of basic metal oxide or salt added. This 

promoter will chemically react with the HCl. This chemical reaction is faster than 

chemisorption and is the dominant form of HCl removal until the promoter is exhausted. 

Once this is reached the HCl is removed by chemisorption as with the activated 

aluminas. From the point of promoter exhaustion onwards, the adsorbed HCl will 

increase the acidity of the surface of the alumina granule. 








HCl Transformation occurs when HCl inlet a chloride removal bed is transformed to 

organic chlorides or into chloride salts which are not retained by the bed and flow out with 

the carrier stream. This occurs over acidic alumina sites and the process is accelerated 

in the presence of adsorbed HCl, adsorbed water and unsaturates (please see section D 

on by-product formation overleaf). There is evidence to suggest the organic chloride 

formation occurs in the top layers (down flow mode) of alumina beds. The entire organic 

chloride reaction front has been observed to be contained in as little as 0.5 meters depth. 

Adsorbed HCl on the alumina surface appears to initiate organic chloride formation and 

this involves all of the HCl entering the reactor. Organic chlorides are difficult to detect 

and frequently lead to the false assumption that HCl is being removed and retained by 

the alumina bed on line. 

4.4 BY-PRODUCT FORMATION 

The Vulcan Series - VGP CRT 2000/3000 are not adsorbents but are true catalyst. 

They have been specifically manufactured to a low surface area and its constituent 

materials (a proprietary doubly promoted and highly porous ceramic support) do not have 

adsorption properties. HCl therefore does not exist freely or in an adsorbed or in a 

partially dissociated state inside the catalyst or on its surface. VGP CRT 2000/3000 is 

not acidic and greatly minimizes organic chloride synthesis or 

condensation/polymerization reactions. 

Alumina Side Reactions 

Alumina itself is slightly acidic in nature because of its ability to donate protons its surface 

hydroxyl groups. Once it has adsorbed hydrogen chloride its surface acidity is increased 

dramatically and this acidity can cause undesirable side reactions to occur in the process 

stream: 

a) In normal operation there will be small traces of unsaturates in the reformer 

reactor product, which will go into both the offgas and reformate streams. For 

example in hydrogen gas ex catalytic reformers the concentration of unsaturates 

varies from 400 ppmv to 1000 ppmv. These unsaturates will react with hydrogen 

chloride when promoted by an acid catalyst. Thus organic chlorides can be 

formed across the alumina bed. These organic chlorides are not removed by the 

alumina and will slip from the bed into the product stream. If the offgas stream 

goes to hydrotreating or hydrocracking units these organic chlorides will be 

hydrogenated to HCl and will then cause corrosion problems and may also 

deactivate the hydroprocessing catalyst. 








The evidence to support this comes from a number of sources: 

o 

o 

o 

Olefins reacting with HCl across aluminum chloride is a well-known, 

industrially used reaction 

Some operators have identified organic chlorides in the exit stream, 

chlorobutane being the most common 

Many operators have noted significant levels of chloride related problems 

(e.g. 

fouling and corrosion) in their downstream hydrotreaters which are nominally 

protected by the alumina beds. 

b) Aromatic hydrocarbons such as benzene will react with any organic chlorides 

present across the acidic alumina to form a higher MW hydrocarbon by the 

Friedel Crafts reaction: 

C6H6 + RCl C6H5R + HCl 

C6H5R + RCl C6H5R-R +HCl 

This 'condensation/polymerization' reaction can occur repeatedly and build up 

hydrocarbons of such high MW that they precipitate out fouling and blocking 

equipment. Some operators report problems of 'green oil' contaminating and 

blocking the alumina bed, downstream valves etc. In other refineries they 

describe the foulant as polycyclic aromatics. In most cases in fact the 'gunge' is 

a complex mixture of aromatic and aliphatic compounds with chlorine and 

oxygenated molecules part of the structure. 

These problems are exacerbated in plants where the degree of vapor/liquid 

separation at the separator drum is poor and there is a higher level of carryover 

of the aromatic rich reformate into the offgas stream. 

The evidence to support this comes from a number of sources: 

- The Friedel Crafts reaction is a well-known organic chemistry reaction 

- Observations of various plant operators. 








5. FAQ: VGP CRT 2000 & 3000 

1. Does your catalyst give off any byproducts as a result of the HCl reaction 

mechanism ? 

No by-products are formed ( eg PCA's - "green oils" or organic chlorides ), however, the 

HCl is removed by chemical reaction, resulting in the production of 1 mole of H 2 O and no 

C0 2 evolution, as is the case with some competitive chloride guards containing 

“carbonates”. This is very important as carbon oxides can have a deleterious impact on 

Isomerization catalyst, when the make gas from the catalytic reformer is used as feed gas 

to the Isomerization Unit. 

2. What is the impact of H 2 O, 1 to 50 ppm, on the catalyst in either the vapor or liquid 

phase? 

Water concentration: Reasonable quantities of water (0.1 %) are necessary to achieve a 

reasonable degree of chloride loading on competitive alumina based adsorbents / 

absorbents; however the performance of VGP CRT 2000 & 3000 requires significantly 

less water. Thus H 2 O vapor in the aforementioned range will have no mal-affect on the 

performance of VGP CRT 2000 & 3000. 

3. What will be the impact of higher levels of halogens for short periods of time? Will 

the catalyst remove all of the chlorides down to the 0.1 ppm level or will the outlet 

concentration increase? 

The unique structure and composition of the CRT Series catalyst, based on its 

engineered shape with relatively high geometric surface area, allows for fast and 

efficient catalytic reaction, with HCl hitting the surface of the catalyst. 

Both the low and high temperature CRT catalyst has been specifically formulated to 

give an optimum density and high availability of the active ingredients, which means 

exceptionally high levels of chloride loading, can be achieved. It is inherent to systems 

using reactive adsorption that they will have higher chloride saturation capacities than 

systems using chemisorption for HCl removal. Chemisorption based systems can only 

count on a monolayer of HCl chemisorbed on to the surface. On the other hand 

chemical reaction (reactive adsorption) systems utilize the whole catalyst volume to 'lock 

in' the chloride. The HCl mass transfer zone when using VGP CRT 2000 & 3000 is small 

in relation to that achieved by competitive materials. It is the combination of realistically 

achievable saturation loading and the mass transfer zone that will determine the average 

chloride loading at EOR. 








The above will vary and will depend very much on the conditions surrounding a particular 

vessel. As a result higher levels of chlorides for short periods of time will be contained in 

the mass transfer zone, enabling VGP CRT 2000 & 3000 to nevertheless achieve its exit 

design specification of < 0.1 ppmv. 

4. What is the impact of liquid carryover into the vapor phase vessel? Will it impact 

the catalyst performance? 

Liquid carryover increases the diffusion resistance in the vapor phase mode. Substantial 

liquid carryover or condensation over any fixed bed normally will mask the active surface 

of granulated materials to the point where the HCl in the process gas will be unable to 

come into contact with the surface of the HCl removal material. 

A properly engineered shaped extrudate, is least effected by this phenomena, as the 

mean free path of diffusion is considerably shorter. 

VGP CRT 2000 & 3000 will recover from reformate or light ends 

impingement/condensation as long as it is appropriately dried out. All other materials will 

not recover because of the incidence of polymerization and simple adsorption. Monitoring 

the evolution of the mass transfer zone down the bed and monitoring liquid carryover will 

forewarn you of these problems. 

If VGP CRT 2000 & 3000 is subjected to reformate wetting, and there is a detectable 

impact on performance, VGP CRT 2000 & 3000 performance can be recovered after 

gentle on line drying and heating. Monitoring of crud carryover inlet the bed is 

recommended because of the potential of bed plugging. These solids will invariably have 

damaged the performance of the coalescer mesh inside the product separation drum. 

The discovery of crud is a sign of gross liquid carryover as a gas phase in itself would not 

be able to carry solids in measurable quantities for any significant distance. 

5. What is the impact of olefins in the vapor phase, up to 0.5 vol%? 

In normal operation there will be small traces of olefins in the reformer reactor product, 

which will present in both the offgas and reformate streams. These olefins will react with 

hydrogen chloride when promoted by a acid catalyst ( alumina ). Thus organic chlorides 

can be formed across the alumina bed. These organic chlorides are not removed by the 

alumina and will slip from the bed into the product stream. If the offgas stream goes to 

hydrotreating or hydrocracking units these organic chlorides will be hydrogenated to HCl 

and will then cause corrosion problems and may also deactivate the hydroprocessing 

catalyst. 








However, the Vulcan Series VGP CRT chloride guards do not utilize alumina to remove 

the hydrogen chloride. Rather they are chemical absorbents. They remove the hydrogen 

chloride by a non-reversible chemical reaction between HCl and the absorbent itself to 

form a neutral salt product, which remains as part of the absorbent particle. Nevertheless, 

if the feed contains significant quantities of polymerization precursors, the possibility 

exists for fouling the surface of the catalyst. 

6. What analytical methods are used to measure chloride concentrations in vapor and 

liquid phases down to 0.1 ppmv levels? Do you have any specific information (i.e. 

analyzer type etc.) on these methods? 

For detection of chlorides in liquid hydrocarbon streams we recommend the following 

methods: 

For detection of inorganic chlorides 

Use of silver nitrate back titration on the water washings of a known quantity of the 

hydrocarbon liquid. Full details are available on request from GBHE C 2 PT. 

GBHE C 2 PT experience indicates that this type of analysis is reliable for detecting ppmv 

quantities of inorganic chlorides but less reliable for sub-ppmv levels. Thus it is OK for 

quick, regular checking that the chloride has not broken through the bed. 

For detection of organic and inorganic chlorides 

Use a GC and Hall detector system. The GC system splits up the different types of 

chloride so that they can be separately identified by the Hall detector. The Hall 

detector converts all the chlorides present to HCl (H 2 is added) and this is then 

specifically detected by the Hall detector (which is a conductivity cell). 

The detector/GC system typically costs about $ 45,000 and can be supplied by the 

American company Varian 








6.0 Performance Monitoring: 

We would recommend that the chloride absorber vessels be manufactured with several 

gas sampling points running down each vessel as this would give you an idea of the 

progression of the mass transfer zone with time. GBHE C 2 PT could confirm the HCl 

profiles versus time on line and versus bed depth. It would also give us a chance to 

confirm bed utilization (average Cl content of bed for EOR conditions) - which does vary 

with bed dimensions. 

Knowing the shape of the mass transfer zone while the charge is on line would also alert 

you of any problems that the charge would be experiencing. These problems could be 

reformate carry over, crud impingement, green oil impingement or light ends 

condensation. These problems can be remedied while the charge is on line if using VGP 

CRT 2000 / 3000 

7.0 Flow Direction - Vapor Phase Sorber 

GBHE C 2 PT recommends that the vapor phase sorber vessel be designed to have the 

net hydrogen flow in the upflow direction. In this case it would also be necessary to have 

a bleed valve arrangement at the bottom of the vessel. Upflow would decrease the effects 

of liquid or solids carry over and its liquid concentration effect would give you an advance 

warning of carry over before the majority of the bed will feel its effect. 

8.0 Process Gas Pressure 

It is best to operate at a high pressure. This will have the tendency of decreasing the 

mass transfer zone and of increasing bed utilization. In geographic locations, which 

dictate a substantial process gas temperature difference between summers and winter 

months, higher pressures will encourage light ends condensation over the granular beds. 

This is a small disadvantage of higher pressures. It can be corrected by the proper use of 

insulation and process gas heating prior the beds via heat exchangers or steam tracing. 

9.0 Process Gas Temperature 

The vessel spot temperature is not a particularly relevant parameter as long as VGP CRT 

2000 / 3000 is thermally stable > 500 oF. The spot temperature has also got to be above 

the deemed process gas dew point. What is important is what has happened upstream 

and what the separation drum or re-contactor temperature is. In general high absorber 

temperatures are an indication of malfunctioning coolers post compression leading to 

light ends deposition down the line. 








10.0 Re-contactor / Separation Drum 

This stage will basically determine whether the fixed bed HCl trap downstream will 

perform or not. The idea is to operate as to minimize the 'heavies' content of the net 

hydrogen ex catalytic reformer. This is done via the highest pressure and lowest 

temperature possible at this stage. It would be good to have the separation drum running 

at a temperature lower than ambient. This is seldom achieved mostly because existing 

plant has not been designed with the optimum operation of HCl absorbers in mind. 

Vulcan Series VGP CRT 2000 / 3000: Analytical Procedures 

What analytical methods are used to measure chloride concentrations in vapor and liquid 

phases down to 0.1-ppm levels? Do you have any specific information (i.e. analyzer type 

etc.) on these methods? 

For detection of chlorides in liquid hydrocarbon streams we recommend the following 

methods: 

For detection of inorganic chlorides 

Use of silver nitrate back titration on the water washings of a known quantity of the 

hydrocarbon liquid. Full details are available on request from GBHE C 2 PT. 

GBHE C 2 PT experience indicates that this type of analysis is reliable for detecting ppmv 

quantities of inorganic chlorides but less reliable for sub-ppmv levels. Thus it is OK for 

quick, regular checking that the chloride has not broken through the bed. 

For detection of organic and inorganic chlorides 

Use a GC and Hall detector system. The GC system splits up the different types of 

chloride so that they can be separately identified by the Hall detector. The Hall detector 

converts all the chlorides present to HCl (H2 is added) and this is then specifically 

detected by the Hall detector (which is a conductivity cell). 

The detector/GC system typically costs about $ 45,000 and can be supplied by the 

American company Varian. 

For detection of organic chlorides - Solids & Liquids 

. 

Total Organic Halogen Measurement System 

Model TOX - 10 ( AOX /POX/EOX ) 

Mfgr. by: Mitsubishi Kasei Corp.

Vulcan Series Chloride Removal Technology VGP CRT 2000 and ...

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