The Uhde STAR process

Oxydehydrogenation oflight paraffins to olefins

ThyssenKrupp Uhde

1. Company profile 3

2. Introduction 42.1 Steam reforming and olefin production plants by Uhde 7 3. Oxydehydrogenation basic principles 8

4. STAR process technology 94.1 STAR catalyst 9 4.2 Process pressure 9 4.3 Operation cycle 9 4.4 Oxidant 104.5 Space-Time-Yield 104.6 STAR process reaction section 104.7 Heat recovery 104.8 Gas separation and fractionation 11

5. Proprietary equipment 135.1 STAR process reformer 135.2 STAR process oxyreactor 14

6. Comparison of dehydrogenation technologies 166.1 General remarks 166.2 Adiabatic reactors connected in series 166.3 Parallel adiabatic reactors 176.4 STAR process with oxydehydrogenation step 17

7. Application of the STAR process 187.1 Oxydehydrogenation of propane to propylene 187.2 Oxydehydrogenation of butanes 197.2.1 Oxydehydrogenation for the production of alkylate 197.2.2 Oxydehydrogenation for the production of dimers 21

8. Services for our customers 23

Table of contents

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Company profile

With its highly specialised workforce of more than 4,500 employees and its international network of subsidiaries and branch offices, Uhde, a Dortmund-based engineering contractor, has, to date, successfully completed over 2,000 projects throughout the world. Uhdes inter- national reputation has been built on the successful application of its motto Engineering with ideas to yield cost-effective high-tech solutions for its customers. The ever-increasing demands placed upon process and application technology in the fields of chemical processing, energy and environmental protection are met through a combination of specialist know-how, comprehensive service packages, topquality engineering and impeccable punctuality. The extensive international experience in the design and construction of chemical plants makes Uhde the ideal licensor and engineering contractor for dehydrogenation plants using the advanced STAR process.

Uhdes head office

Dortmund, Germany

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2. Introduction

STAR, which is the acronym for STeam Active Reform-ing, is a commercially established dehydrogenation tech- nology that was initially developed by Phillips Petroleum Company, Bartlesville, OK, USA.

Uhde acquired the technology including process know-how and all patents related to process and catalyst from Phillips in December 1999.

Medium and long-term forecasts expect to see a growing demand for on-purpose technologies for olefin pro duction (e.g. propylene, butylenes) such as dehy-drogenation of light paraffins.

Today most propylene is produced as co-product in steam crackers (approx. 57%) and as by-product in FCC units (approx. 35%). Only approx. 6 - 8% is produced by on-purpose technologies like propane dehydrogen-ation (PDH) or metathesis.

However, higher annual growth rates for propylene than for ethylene are expected. Additionally, steam cracking increasingly shiftsto ethane feedstocks due to more favourable economics compared to naphtha or LPG feedstocks. Because ethane cracking yields consider-ably less propylene than LPG or naphtha cracking this will result in a gap for supply of propylene. This gap can very economically be closed by propane dehydro-genation applying the STAR process.

Rapid further growth is expected for on-purpose pro-pylene and butylene production to yield the following derivatives:

Derivates of Propylene Derivates of Isobutylene

Polypropylene* MTBE/ETBE

Propylene Oxide** Alkylate

Cumene Dimers

Acrylonitrile MMA

Acrylic Acid Alcohols/MEK

Oxo-Alcohols Butyl Rubber

*Authorized Contractor **Own technology with Evonik

Coastal Chemical Inc. in Cheyenne, Wy, USA,

Capacity: 100,000 t/y isobutene

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Two commercial units applying the STAR process tech- nology have been commissioned for the dehydrogen- ation of isobutane integrated with the production of MTBE:

Coastal Chemical Inc., Cheyenne, Wy, USA was commissioned in 1992 and produces 100,000 tonnes per annum of isobutene.

Polybutenos, Argentina, was designed for a capacity of 40,000 tonnes per annum of isobutene and was commissioned in 1994.

The successful operation of those plants demonstrated the high stability of the STAR catalyst.

In the period from 2000 to 2004 Uhde significantly increased the performance of the STAR process by adding an oxydehydrogenation step.

Uhde has a long and broad experience in design and commissioning of equipment used in STAR process technology as well as plants for production of olefins and olefin derivatives.

In 2006 Uhde was awarded a lump sum turnkey con-tract to build a 350,000 tonne-per-annum PDH/PP com- plex by Egyptian Propylene & Poly-propylene Company (EPP) in Port Said, Egypt.

In 2009 and 2010 two other clients have awarded Uhde contracts for 450,000 tonnes per annum PDH plants.

3-D model of PDH/PP complex for Egyptian Propylene

and Polypropylene Company (EPP)

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2.1 Steam reforming and olefin production plants supplied by Uhde

SINCOR C.A. in Jose, Venezuela,

Capacity: 2 x 97,770 Nm3/h of hydrogen

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Uhde and steam reformingThe references on steam reforming attached hereto re-flect Uhdes experience in connection with the reaction section and steam generation equipment applied in the STAR process. Today the total count is as follows:

Steam reformer: more than 65 units (basis for STAR process reformer)

Secondary reformer: more than 40 units (basis for STAR process oxyreactor)

Uhde and olefinsUhde has also designed and successfully commis-sioned plants for a wide range of applications for production of olefins and olefin derivatives using the technologies described in Table 1. In combination with the STAR process Uhde is in the position to offer complete process routes:

Production of polypropylene (PP) or propylene oxide (PO) from propane.

Production of MTBE or other high octane blend- stocks (e.g. alkylate or dimers) from butane.

Another advantage of the STAR process is the fact that Uhde combines the functions of technology owner/licensor and overall turnkey contractor and is therefore able to provide process performance guaran-tees as well as total plant completion and mechanical guaranties within the framework of a single-point responsibility (turnkey) contract.

Product Process Licensor

Ethylene dichloride Vinnolit

Ethylene oxide Shell Chemicals

Ethylene glycol Shell Chemicals

Propylene oxide Evonik-Uhde

High density polyethylene LyondellBasell

Low density polyethylene LyondellBasell

Polypropylene LyondellBasell

Alkylate UOP, ConocoPhillips, Stratco

MTBE/ETBE Uhde

Dimers Axens, UOP

Olefins Uhde

Table 1:

Uhdes portfolio for

the production of olefins

and olefin derivatives

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3. Oxydehydrogenation basic principles

Dehydrogenation is an endothermic equilibrium reaction. The conversion of paraffins increases with decreasing pressure and increasing temperature. In general pro-cess temperature will increase with decreasing carbon number to maintain conversion at a given pressure. As shown below for propane and butane, respectively, the major reaction is the conversion of paraffin to olefin.

Propane dehydrogenation (PDH):

C3H

8 C3H6 + H2

Butane dehydrogenation (BDH):

C4H

10 C4H8 + H2

Lower hydrocarbons (i.e. lower in carbon number than that of the feedstock) are also formed. Minor reactions that occur are cracking, which is primarily thermal and results in the formation of small amounts of coke.

Obviously conversion is limited by the thermodynamic equilibrium for a given pressure and temperature. As conversion approaches equilibrium, reaction velocity decreases and catalyst activity is not efficiently utilised. However, if oxygen is admitted to the system this will form H

2O with part of the hydrogen, which in turn will

shift the equilibrium of the dehydrogenation reaction to increased conversion. Figure 1 shows the influence of oxygen addition as it shifts the equilibrium towards in-creased conversion of propane to propylene. Formation of H

2O is exothermic and hence provides the heat of

reaction for further endothermic conversion of paraffin to olefin.

Major requirements to achieve this objective are as follows:

The catalyst continues to maintain its activity for dehydrogenation and does not convert the hydrocarbons to carbon oxides and hydrogen (Steam reforming).

The catalyst is stable in the presence of steam and oxygen.

The STAR catalyst fully satisfies those requirements.

Above mentioned advantages are utilised in the STAR process which connects conventional de-hydrogenation (i.e. the STAR reformer) in series with an oxydehydro-genation step (i.e. oxyreactor).

In principle, the concept of oxydehydrogenation has already been commercially proven for the conversion of butene-1 to butadiene (Oxo-D process developed by Petro-Tex Corp.). Seven units were installed (five of them in the USA) between the years 1965 to 1983, with plant capacities ranging from 65,000 to 350,000 tonnes per annum of butadiene. The total installed capacity was over a million tonnes per annum. Oxidant was air.

60

55

50

45

40

25

30

35

540

20

550 560 570 580 590 600

Temperature [C]

Con

vers

ion

Prop

ane

[%]

without OxygenO2 / HC Ratio = 0.05O2 / HC Ratio = 0.1

Figure 1:

Thermody