Selective hydrogenation of acetylene

 

Selective acetylene hydrogenation units plays a fundamental role in the purification of polymer-grade ethylene produced in steam cracker plants and with the increased interest we recently see we expanded our internal capabilities to accelerate the research for selective hydrogenation catalysts . 

Front-end vs Tail-End

Hydrogenation units exist in multiple variants depending on the location of the acetylene hydrogenation reactor(s). The two main designation are typically known as Front-end and Tail-end (or Back-end) [1].

Independently of the locations of the hydrogenation units, they have one thing in common:

Acetylene must be selectively hydrogenated but Why?   

A study for a 800 kTA plant showed that “a differential in catalyst selectivity of 75 percent over its lifetime will result in an additional 48 million pounds per year (21.8 KTA) of ethylene—or over 2.7 percent of the plant’s ethylene capacity” [2], hence the value of accurately assessing the performance of acetylene hydrogenation catalysts before change outs.

Our approach for accelerating catalyst research

Avantium has recently built a dedicated high-throughput unit to evaluate the performance of acetylene hydrogenation catalysts. For this purpose, we use our Flowrence® technology and single-pellet-string reactors (SPSRs), optimized for the operation window as shown on the picture. 

The unit consists of 16 reactors in parallel and multiple operation modes that allows us to simultaneously test 4, 8, 12 or 16 catalysts. In addition, the analysis of the product stream is carried out in a tailored two-channel GC; each containing one TCD and one FID. The GC works with a fast 6-minute method which accurately can analyze C1-C4 hydrocarbons, H2, He and N2.

Currently, we are performing a validation program with a catalyst supplier to optimize the experimental setup and establish the performance of the unit before its release for commercial catalyst testing.

This will enable our customers to determine the catalysts’ operating window and perform stability studies at iso-conversion tests with feedback control loops for reactor temperature control.

In short if you face a challenge on accelerating your selective hydrogenation catalyst development we have a testing solution available to help you.

[1]    Edgar L. Mohundro. Overview on C2 and C3 selective hydrogenation in ethylene plants. In 15th Ethylene Produces Conference, volume 15. AIChE, 2003. Session 64: Ethylene Plant Technology C2 and C3 Hydrogenation Technology Review.

[2]    Darin Tiedtke, T.T. Cheung, Jacques Leger, Stan Zisman, J.J. Bergmeister, and G.A. Delzer. Chemicals influencing the activity of palladium-based catalysts for the selective hydrogenation of acetylene to ethylene in acetylene converters. In 13th Ethylene Producers’ Conference, volume 13. AIChE, 2001. Session 80: Catalyst Poisons in Ethylene Plants.

Flowrence® products specifications

Reactor Section

Easy and quick reactor exchange system. Possibility to use quartz reactors at high pressure.

1 block of 4 reactors

HT = High Temperature max. 800°C nominal, limited to 925°C (<0.5°C reactor to reactor deviation)

4 blocks of 4 reactors

HT  or MT = Medium Temperature max. 525°C (<0.5°C block-to-block deviation)

16 reactors with iRTC

individual Reactor Temperature Control
max. 550°C (<0.5°C reactor-to-reactor)

4 reactors with iRTC

individual Reactor Temperature Control
max. 550°C (<0.5°C reactor-to-reactor)

Temperature Ranges (°C)

100 – 800°C
up 925°C (Option)

50 – 525°C
100 – 800°C
up 925°C (Option)

50 – 550°C

50 – 550°C

Reactor Types

L= Length
OD= Outer Diameter
ID= Inner Diameter
SS= Stainless Steel (< 550⁰C)
Qz= Quartz (< 925⁰C)

L 300 mm 561 mm
OD 3 mm 6 mm
ID SS 2 / 2.6 mm 2 / 3 / 4 / 5 mm
ID Qz 2 mm 2 / 4 mm
300 mm 561 mm 561 mm
3 mm 3 mm 6 mm
2 / 2.6 mm 2 / 2.6 mm 2 / 3 / 4 / 5 mm
2 mm 2 mm 2 / 4 mm
561 mm
3 mm
2 / 2.6 mm
2 mm
561 mm
3 mm
2 / 2.6 mm
2 mm

Maximum Catalyst Bed Length

(isothermal zone tolerance ± 1°C)
Note: isothermal length is dependent on the temperature range

300 / 3 HT 561 / 6 HT
>120 mm @ 450°C >200 mm @ 500°C
>90 mm @ 800°C >150 mm @ 800°C
>140 mm @ 925°C
300 / 3 HT 561 / 3 MT 561 / 6 HT
>120 mm @ 450°C >310 mm @ 450°C >200 mm @ 500°C
>90 mm @ 800°C >150 mm @ 800°C
>140 mm @ 925°C
561 / 3 MT iRTC
250°C ±0.5°C 41cm (4reactors)
350°C±0.5°C 38cm (4reactors)
550°C±0.5°C 28cm (4reactors)
3 reactors at 550°C, 1 reactor 350°C:
550°C=27cm 350°C=41cm ±0.5°C
561 / 3 MT iRTC
250°C ±0.5°C 41cm (4reactors)
350°C±0.5°C 38cm (4reactors)
550°C±0.5°C 28cm (4reactors)
3 reactors at 550°C, 1 reactor 350°C:
550°C=27cm 350°C=41cm ±0.5°C

Catalyst Volume (mL)

(isothermal zone)

0.2 - 0.6 mL 0.4 - 2.0 mL
0.2 - 0.6 mL 0.4 - 1.0 mL 0.4 - 2.0 mL
0.4 - 1.0 mL
0.4 - 1.0 mL

Pressure Ranges (barg)

2 – 80 barg
0.5 – 180 barg (option)

2 – 100 barg
0.5 – 180 barg

2 – 80 barg
0.5 – 180 barg

2 – 20 barg
2 – 50 barg (option)

Reactor Pressure Control

Advanced control RSD ±0.1 barg at reference conditions (gas phase only and 20 barg). For trickle flow Advanced control RSD ±0.5barg.

Standard (±0.5 barg)
Advanced (±0.1 barg) (option)

Standard (±0.5 barg)
Advanced (±0.1 barg) (option)

Advanced (±0.1 barg)

Advanced (±0.1 barg)

Gas Feed Lines

(#Gas Feeds)

Up to 6 + Diluent gas

He, Ar, N2, H2, CH4, CO2, C2H4, C2H6, O2/Inert (≤5%), CO, Other gases

Up to 7 + Diluent gas

He, Ar, N2, H2, CH4, CO2, C2H4, C2H6, O2/Inert (≤5%), CO, Other gases

Up to 7 + Diluent gas

He, Ar, N2, H2, CH4, CO2, C2H4, C2H6, O2/Inert (≤5%), CO, Other gases

Up to 6 + Diluent gas

He, Ar, N2, H2, CH4, CO2, C2H4, C2H6, O2/Inert (≤5%), CO, Other gases

Online Analysis

Full integration GC, MS , GC/MS with data visualisation (option)

Full integration GC, MS , GC/MS with data visualisation

Full integration GC, MS , GC/MS with data visualisation

Full integration GC, MS , GC/MS with data visualisation

Liquid Feed

 Split feeding 8 + 8 reators (option)

Pump-Coriolis dosing system
(ambient, cooled)

Pump-Coriolis dosing system
(ambient, cooled, heated 80°C)

Pump-Coriolis dosing system
(ambient, cooled, heated 80°C)

Pump-Coriolis dosing system
(ambient, cooled, heated 80°C)

Liquid Distribution

Microfluidic Distribution
(4-channel glass-chip)

Microfluidics Distribution
(4x4-channel glass-chip)
(16-channel glass-chip)
Active Liquid Distribution (option)
(with automatic isolation valves)

Active Liquid Distribution
(with automatic isolation valves)

Microfluidic Distribution
(4-channel glass-chip)

Liquid Sampling

(G/L Separation)

Parallel liquid sampling (4 x 20ml vials) with sequential on-line gas phase sampling (option)

Automated liquid sampling (4 rows x 16 vials x 8ml) with sequential on-line gas phase sampling (option)

Automated liquid sampling (4 rows x 16 vials x 8ml) with sequential on-line gas phase sampling (option)

Parallel liquid sampling (4 x 20ml vials) with sequential on-line gas phase sampling (option)

Reactors Effluent Handling

(Off-line Analysis Connection)

Full heated circuit up to 180°C with sequential on-line full gas phase sampling (option)

Full heated circuit up to 200°C with sequential on-line full gas phase sampling

Full heated circuit up to 200°C with sequential on-line full gas phase sampling

Full heated circuit up to 200°C with sequential on-line full gas phase sampling

Offline Analysis

Integrated Workflow: SimDist, total S/N, liquid density, balance, label printer, barcode (option)

Integrated Workflow: SimDist, total S/N, liquid density, balance, label printer, barcode

Integrated Workflow: SimDist, total S/N, liquid density, balance, label printer, barcode

Integrated Workflow: SimDist, total S/N, liquid density, balance, label printer, barcode

Waste Handling

Ambient temperature
Heated wax trapping (option)

Ambient temperature / Cooled containers / Heated compartment (wax trapping, heavies)

Ambient temperature / Cooled containers / Heated compartment (wax trapping, heavies)

Ambient temperature / Cooled containers / Heated compartment (wax trapping, heavies)

Safety

Gas sensors and control box (CO, LEL, VOC)

Gas sensors and control box (CO, LEL, VOC)

Gas sensors and control box (CO, LEL, VOC)

Gas sensors and control box (CO, LEL, VOC)

Flowrence® Software

Flowrence® recipe builder, control & database builder

Flowrence® recipe builder, control & database builder

Flowrence® recipe builder, control & database builder

Flowrence® recipe builder, control & database builder

Microfluidics modular gas distribution

Unrivalled accuracy in gas distribution with patented glass-chips for 4 and 16 reactors, with a guaranteed flow distribution of 0.5% RSD. Quick exchange of glass-chips for different operating conditions. Flexibility to cover a wide range of applications.

TinyPressure glass-chip holder with integrated pressure measurement

Compact modular design for gas and liquid distribution. No high-temperature pressure sensors required. Quick exchange of the microfluidic glass-chips, without the need for time-consuming leak testing.

Tube-in-tube reactor technology with effluent dilution

Unique tube-in-tube design with easy and rapid exchange of the reactor tubes (within minutes!). No need for any connections. Use of inert diluent gas (outside of reactor) to maintain the pressure prevents dead volumes and back flow. Possibility to use quartz reactors at high pressure applications.

Automated liquid sampling system

Programmable, fully automated liquid product sampling robot for 24/7 hands-off operation. Robot equipped with a compact manifold aiming at depressurizing the effluent immediately after each reactor to atmospheric pressure. Eliminates the use of high pressure valves.

Reactor Pressure Control (RPC)

The most accurate and stable pressure regulator for a 16-parallel reactors with just ±0.1bar RSD. The RPC uses microfluidics technology to regulate the pressure of each reactor, maintaining equal distribution of the inlet flow over the 16 reactors.

Auto-calibrating liquid feed distribution, measurement, and control

Distribution of difficult feedstocks e.g., VGO, HVGO, DAO. Liquid distribution 0.2% RSD, making it the most accurate liquid distribution device on the market. Option to selectively isolate each reactor.

Single-Pellet-String-Reactors (SPSR)

No dead-zones, no bed packing & distribution effects. The catalyst packing is straightforward and does not require special procedures. A single string of catalyst particles is loaded in the reactors avoiding maldistribution, eliminating channeling and incomplete wetting.

EasyLoad®

Unique reactor closing system with no connections. Rapid reactor replacement minimizing delays, improving uptime and reliability. Stable evaporation by liquid injection into reactor.

Contact us

We are here to help you

 

 

 

 

 

 

 

 

Avantium Headquarters

+31 (0)20 586 8080

Zekeringstraat 29
1014 BV Amsterdam
The Netherlands

Contact us