Comparative Analysis of Oxy Reactor Catalyst

8/19/2019 Comparative Analysis of Oxy Reactor Catalyst

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COMPARATIVE ANALYSIS OF OXY REACTOR CATALYSTS

Prepared By:Saad Arif

Reviewed By: SHS

Submitted To:

Copy To:

Date: 04 January 2015

Subject: Comparison of performance parameters for OXY reactor catalyst

between OXY MAX-A and OXY CHLOR 8C and determination of gains madeafter switching to OXY Chlor 8C

BACKGROUND

VCM plant at this site is relocated plant from Formosa Plastics Corporation, Baton

Rouge, LA, USA. The plant was relocated to Pakistan in 2006-07 and was eventually

commissioned in 2009. At the time of commissioning, EPCL, being in an agreement with

INEOS Vinyl for the LTC reactors, procured the INEOS based OXY reactor catalyst. The

catalyst is commercially known as IVOC-FB2. EPCL continued to use the INEOS based

catalyst till Dec-2012

In 2012, EPCL decided to negotiate a technical services agreement with VINNOLIT.

While the technical services agreement could not materialize, during correspondence,

VINNOLIT offered its trademark OXY reactor catalyst, commercially known as OXY

MAX. EPCL decided to change the reactor catalyst. Approximately 15met of OXY MAX-

A was added to the OXY reactor in January-2013 and by July-2013, the reactor was

operating with a full set of OXY MAX-A.

In 2014, EPCL approached OXY Vinyl for a technical services/licensing agreement. The

licensing contract was finalized with Oxy Vinyl and the discussion concluded that the

use OXY Vinyl patented OXY reactor catalyst will result in improved performance of the

OXY reactor at EPCL. It was decided to switch from OXY MAX-A to BASF based

catalyst commercially known as OXY CHLOR 8C.

From September 2015 to November 2015, 5 tons of OXY CHLOR 8C was charged to the

reactor each month and by December 2015, the reactor is operating with mixed catalyst

of which approximately 40% is OXY Chlor 8C.


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SCOPE

The scope of this position paper is to compare the performance of OXY MAX and OXY

Chlor 8C and assess whether the shift from CLARIANT based catalyst to BASF based

catalyst has resulted in improved reactor performance or not.


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BASIS

OXY reactor performance is evaluated for the months of June-December 2015. From

June-August 2015, OXY reactor was charged with 100% OXY MAX. Efficiency and

performance of OXY Max can be evaluated by analyzing OXY reactor performance in

this interval.

As a remake, OXY Chlor 8C has been charged from September 2015 to November 2015.

During this period, OXY reactor is operated with mixed catalyst. The percentage of OXY

Chlor 8C increased from 12.5% to 40%.

Since OXY reactor is not charged yet with 100% OXY Chlor 8C, it is not possible to

assess the actual performance of OXY Chlor 8C, but the improvements occurred since

the charging of OXY Chlor 8C has been started can be gauged.

At this moment, we can compare the performance, and gauge the improvements caused

by switching to OXY Chlor 8C.

CATALYST OVERVIEW

The catalyst employed in the OXY reactor is Cupric Chloride (CuCl2). This catalyst is

highly selective for EDC reaction. Catalyst activity is a measure factor which varies with

temperature. Reactor operation at the optimal temperature with correct feed ratios is

required to prevent the formation of impurities and enhanced efficiencies.

CLARIANT-

QUOTED+

BASF-QUOTED*

Ethylene Efficiency (%) 95.8 95.8

HCl Conversion (%) 99.0 99.6

EDC Purity (%) 98.8 98.8

Catalyst Loss(kg/t-edc) 0.1 0.1

+ Data for OXY MAX-A * Data for OXY CHLOR 8C

OPERATING CONDITIONS

OXY reactor operating parameters play a key role in the OXY reactor performance. The

three most important parameters are load, temperature and ethylene to HCl ratio. For

this analysis, low load operation is not considered since the performance indicators are


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not the true indicators of OXY reactor performance when the OXY reactor is operated

under low load conditions.

Parameters Uni

t

Only OXY

MAX

12.5% OXY

Chlor 8C

25% OXY

Chlor 8C

40% OXY

Chlor 8C

Temperature °C 240 236 236 235

Load TPH 12.6 13.7 13.6 13.5

Ethylene/HCl 0.4 0.4 0.4 0.4


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COMPARATIVE ANALYSIS OF CATALYSTS:

The main function of OXY reactor catalyst is to increase the specificity and efficiency of

the reaction, and provide good heat transfer between the reaction zone and the cooling

coils.

Performance of the OXY reactor catalyst can be gauged on the basis of following

parameters:

I. Ethylene Efficiency

II. HCl Efficiency

III. Product quality

IV. Catalyst Consumption

Following table provides a comparison between the afore-mentioned parameters.

Comparison has been drawn to compare the performance of OXY Max and OXY Chlor

8C.

Only OXY

MAX

Mixed

Catalyst

Mixed

Catalyst

Mixed

Catalyst

% of Oxy Chlor 8C 0 12.5 25 40

Efficiencies

Ethylene Efficiency, % 95.8 95.6 95.5 95.3

HCl Efficiency, % 97.9 99.1 99.1 99.3

Product Quality

1,2-EDC, % 98.3 98.6 98.7 98.7

T/LBM, % 0.6 0.4 0.4 0.4

T/HBM, % 1.2 0.95 0.9 0.9

Catalyst consumption,kg/t-EDC

0.2 0.2 0.2 0.2

Vent Gas Composition

Ethylene, % 0.27 0.48 0.46 0.51

CO2, % 1.59 1.61 1.63 1.7

CO, % 0.84 0.73 0.75 0.75

O2, % 3.65 3.61 3.46 3.86


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ETHYLENE EFFICIENCY:

Ethylene efficiency is the measure of ethylene conversion as well as ethylene selectivity

to produce 1,2-EDC. Inefficiency is due to ethylene consumption in oxidation reactionand unreacted ethylene in vents.

It is evident from the afore-mentioned data that the ethylene efficiency has encountered

a decreasing trend. Since the charging of OXY Chlor 8C has been started, there is a

slight decrease observed in the ethylene efficiency. Percentage decrease in ethylene

efficiency is0.52%.

HCL EFFICIENCY:

HCL efficiency is the measure of total HCl consumed in OXY reactor.

When the reactor was fully charged with OXY Max, HCl efficiency was consistently low

and has an average of 97.9%.

Since the charging of OXY Chlor 8C has been started, HCl efficiency has encountered a

significant increase and has increased up to 99.3%. Percentage increase in HCl efficiency

is1.43%.

PRODUCT QUALITY

Main reaction mechanism of OXY reactor is the EDC reaction in which ethylene, HCl

and oxygen react in the presence of a catalyst (CuCl2) to produce 1,2-EDC and water.

In OXY reactor there are other reactions taking place as well. These reactions result in

the formation of low boiling materials and high boiling materials along with 1,2-EDC.

These LBM and HBM are produced by the reaction of ethylene/HCL/EDC via various

reaction paths and impact OXY reactor product quality.

Product quality of OXY reactor should be in the range of 99.1-99.5% provided that thehydrogenator is employed to hydrogenate acetylene in the HCl feed to ethane and

ethylene. Since the plant commissioning, hydrogenator is not employed due to the

unavailability of catalyst and the lower bound of product quality has been set at 98.5%.

When the OXY reactor was fully charged with OXY Max, product quality had remained

low at an average value of 98.3%.

Since the charging of OXY Chlor 8C has been started, there is a gradual rise in the

product quality and it has increased to 98.7% on average.

Percentage increase in the product quality is0.41%


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CATALYST CONSUMPTION

Fines generation is the characteristic of fluidized bed reactor and fines removal is

essential for good fluidization. It is necessary to periodically charge fresh catalyst in the

OXY reactor to maintain the catalyst level inside the reactor.

Since the charging of OXY Chlor 8C started, there is no decrease in catalyst loss has

been observed.


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CONCLUSION

It can be misleading to look at a single indicator and draw conclusions based on that

indicator alone. In order to draw conclusion regarding effectiveness of OXY Chlor 8C, all

the indicators need to be considered.

Performance highlights

Ethylene Efficiency: Percentage decrease of 0.52%

HCl Efficiency: Percentage increase of 1.43%

Product Quality: Percentage increase of 0.41%

Catalyst Consumption: No significant decrease observed

Since the OXY Chlor 8C charging has been started, there is a decrease observed in

ethylene efficiency. It should not be forgotten that at EPCL Ethylene/HCL (0.4) is quite

higher than stoichiometric (0.384).

This decrease is accompanied with increase in ethylene and oxides in vents but the

increase in unreacted ethylene is greater than increase in oxides. This relationship

indicates that the OXY reactor Ethylene to HCl ratio can be trimmed and ethylene

efficiency can be improved with lower excess ethylene consumption.

Improvement in EDC purity has benefitted our downstream purification and cracking

units as well with furnace feed purity risen up to 99% and AS-303 bottom EDC purity to

98%.

Improvement in HCl efficiency has resulted in monetary savings, ensured system

integrity and reduced caustic consumption.

With OXY Chlor 8C periodic charging, performance parameters are showing

improvement and it is believed once the entire catalyst will be replaced performance

parameters will acquire near to the BASF quoted parameters.

On comparing EDC purity and HCl efficiency, it can be concluded that BASF based

catalyst OXY Chlor 8C has brought improvement in the OXY reactor performance.

WAY-FORWARD

It is expected that the OXY Chlor 8C will replace the existing catalyst by May 2016 and

it will be possible to gauge OXY Chlor 8C actual performance against BASF quoted

performance parameters.


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In order to improve ethylene efficiency, Ethylene to HCl ratio can be reduced and the

results can be assessed then.

With the improvements obtained in HCl efficiency and product quality, EPCL should

continue the use of OXY Chlor 8C.

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