Improvement of Pt-based catalyst supported on CeZrO2 used for the high-temperature water-gas shift reaction
(2022) KETM05 20212Chemical Engineering (M.Sc.Eng.)
- Abstract (Swedish)
- The iron-chromium (Fe/Cr) catalyst is used for high-temperature water-gas shift (HT WGS) reaction. A major concern using the Fe/Cr catalyst is that it contains hexavalent chromium (Cr+6) which is a potent carcinogen causing health and environmental issues. In order to reduce the usage of chromium in industrial HT WGS applications, a chromium-free catalyst needs to be developed. The aim of this thesis project was to develop a chromium-free catalyst which shows high activity, selectivity, and stability during HT WGS operating conditions.
Six different formulations, catalysts A-F, were prepared for the experimental part of the project. The prepared catalysts were then compared to the activity and selectivity performance of a
commercial... (More) - The iron-chromium (Fe/Cr) catalyst is used for high-temperature water-gas shift (HT WGS) reaction. A major concern using the Fe/Cr catalyst is that it contains hexavalent chromium (Cr+6) which is a potent carcinogen causing health and environmental issues. In order to reduce the usage of chromium in industrial HT WGS applications, a chromium-free catalyst needs to be developed. The aim of this thesis project was to develop a chromium-free catalyst which shows high activity, selectivity, and stability during HT WGS operating conditions.
Six different formulations, catalysts A-F, were prepared for the experimental part of the project. The prepared catalysts were then compared to the activity and selectivity performance of a
commercial Fe/Cr catalyst. The tests were performed in a reactor containing 3 ml of the catalyst and 3 ml of inert material (alfa-alumina). The particle size of the catalysts and the inert material was 1-2 mm. Feed containing 10.8 % CO, 29.8 % H2O, 43.2 % H2 and 16.2 % CO2 was mixed and introduced to the reactor (Gas hourly space velocity: 20,000 h
-1). The outlet dry gas was analysed by gas chromatography at temperatures 350 °C, 400 °C, 450 °C and 500 °C. The system was
operating at atmospheric pressure. The short-term activity and selectivity tests show that the catalysts E exhibits CO conversion up to 72 % at 350 °C (the maximum CO conversion is 79.3 % at 350 °C due to equilibrium). Compared to the commercial Fe/Cr catalyst, which exhibits 37.8 % at 350 °C, the activity of the catalyst E is significantly higher. None or very low concentrations of hydrocarbons were produced, implying that the catalyst is selective towards the desired products, H2 and CO2. The other prepared catalysts, Pt/Re/CeZrO2 and Pt/Re/TiO2, performed poorly in terms of selectivity. Pt/Re/CeZrO2 produced as much as 5.97 % methane at 450 °C. The Pt/Re/TiO2 catalyst produced 0.16 % methane at 450 °C. Because of the methane formation, it was concluded that the Pt/Re/CeZrO2 and Pt/Re/TiO2 catalyst formulations are not suitable for HT WGS applications, and were therefore not further studied in the long-term stability test.
The long-term stability tests were performed on the catalyst E. No deactivation signs were noted during the 135 hours on-stream and reactor temperature at 400 °C. The thesis project presents successful results from the experiments performed on the developed chromium-free catalyst for HT WGS applications. In terms of the activity and selectivity, it is concluded that catalyst E exceeds the performance of a commercial Fe/Cr catalyst. Stability results show that the catalyst is stable for at least 135 hours, not indicating any deactivation signs. (Less) - Popular Abstract
- As energy demand increases worldwide, the interest in hydrogen has increased as well. Hydrogen is an excellent energy source and an essential component in large industries such as oil refineries, ammonia production plants and methanol synthesis plants. To produce hydrogen, steam methane reforming process is used where methane (CH4) and steam (H2O) is converted to carbon monoxide (CO) and hydrogen (H2). Many industrial applications are demanding pure hydrogen which is not achievable in the steam methane reforming process. Therefore, another important step is required in order to achieve pure hydrogen. This step is called water-gas shift reaction. In this reaction, carbon monoxide (CO) and steam (H2O) react to produce carbon dioxide (CO2)... (More)
- As energy demand increases worldwide, the interest in hydrogen has increased as well. Hydrogen is an excellent energy source and an essential component in large industries such as oil refineries, ammonia production plants and methanol synthesis plants. To produce hydrogen, steam methane reforming process is used where methane (CH4) and steam (H2O) is converted to carbon monoxide (CO) and hydrogen (H2). Many industrial applications are demanding pure hydrogen which is not achievable in the steam methane reforming process. Therefore, another important step is required in order to achieve pure hydrogen. This step is called water-gas shift reaction. In this reaction, carbon monoxide (CO) and steam (H2O) react to produce carbon dioxide (CO2) and hydrogen (H2). In industrial applications, the water-gas shift process is divided in two steps: high-temperature WGS and low-temperature WGS. In this project, the focus was shifted towards the high-temperature step and the catalyst used in this step.
High-temperature WGS reaction is usually operated at temperatures 310 °C to 450 °C and pressures up to 60 bar. The reaction is catalyzed by iron-chromium (Fe/Cr) which is a well-known catalyst used. This catalyst performs great, both in terms of activity and stability. Another advantage is the low cost. However, the main downside is that this catalyst contains hexavalent chromium which causes harm, both to the environment and organisms exposed to it. Due to the toxicity of the hexavalent chromium, there is a need to reduce the usage of iron-chromium catalyst in the industries, therefore many researchers have shifted their focus towards developing a chromium-free catalyst for the high-temperature WGS reaction. The aim of this thesis project was to develop a chromium-free catalyst which shows high activity, selectivity, and stability during HT WGS operating conditions. Six different formulations, catalysts A-F, were prepared for the experimental part of the project. The prepared catalysts were then compared to the activity and selectivity performance of a commercial Fe/Cr catalyst.
The tests were performed in a reactor containing 3 ml of the catalyst and 3 ml of inert material (alfa-alumina). The particle size of the catalysts and the inert material was 1-2 mm. Feed containing 10.8 % CO, 29.8 % H2O, 43.2 % H2 and 16.2 % CO2 was mixed and introduced to the reactor. The outlet dry gas was analyzed by gas chromatography at temperatures 350 °C, 400 °C, 450 °C and 500 °C. The system was operating at atmospheric pressure.
The short-term activity and selectivity tests show that the catalysts E exhibits CO conversion up to 72 % at 350 °C (the maximum CO conversion is 79.3 % at 350 °C due to equilibrium). Compared to the commercial Fe/Cr catalyst, which exhibits 37.8 % at 350 °C, the activity of the catalyst E is significantly higher. None or very low concentrations of hydrocarbons were produced, implying that the catalyst is selective towards the desired products, H2 and CO2. The other prepared catalysts, Pt/Re/CeZrO2 and Pt/Re/TiO2, performed poorly in terms of selectivity. Pt/Re/CeZrO2 produced as much as 5.97 % methane at 450 °C. The Pt/Re/TiO2 catalyst produced 0.16 % methane at 450 °C. Because of the methane formation, it was concluded that the Pt/Re/CeZrO2 and Pt/Re/TiO2 catalyst formulations are not suitable for HT WGS applications and were therefore not further studied in the long-term stability test.
This work present successful results from the experiments performed on the developed chromium-free catalyst for HT WGS applications. In terms of the activity and selectivity, it is concluded that catalyst E exceeds the performance of a commercial Fe/Cr catalyst. Stability results show that the catalyst is stable for at least 135 hours, not indicating any deactivation signs. (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/student-papers/record/9091768
- author
- Grikainyte, Milda LU
- supervisor
- organization
- course
- KETM05 20212
- year
- 2022
- type
- H2 - Master's Degree (Two Years)
- subject
- keywords
- Water-gas shift, catalyst, chemical engineering
- language
- English
- id
- 9091768
- date added to LUP
- 2022-09-06 12:41:25
- date last changed
- 2022-09-06 12:41:25
@misc{9091768,
abstract = {{The iron-chromium (Fe/Cr) catalyst is used for high-temperature water-gas shift (HT WGS) reaction. A major concern using the Fe/Cr catalyst is that it contains hexavalent chromium (Cr+6) which is a potent carcinogen causing health and environmental issues. In order to reduce the usage of chromium in industrial HT WGS applications, a chromium-free catalyst needs to be developed. The aim of this thesis project was to develop a chromium-free catalyst which shows high activity, selectivity, and stability during HT WGS operating conditions.
Six different formulations, catalysts A-F, were prepared for the experimental part of the project. The prepared catalysts were then compared to the activity and selectivity performance of a
commercial Fe/Cr catalyst. The tests were performed in a reactor containing 3 ml of the catalyst and 3 ml of inert material (alfa-alumina). The particle size of the catalysts and the inert material was 1-2 mm. Feed containing 10.8 % CO, 29.8 % H2O, 43.2 % H2 and 16.2 % CO2 was mixed and introduced to the reactor (Gas hourly space velocity: 20,000 h
-1). The outlet dry gas was analysed by gas chromatography at temperatures 350 °C, 400 °C, 450 °C and 500 °C. The system was
operating at atmospheric pressure. The short-term activity and selectivity tests show that the catalysts E exhibits CO conversion up to 72 % at 350 °C (the maximum CO conversion is 79.3 % at 350 °C due to equilibrium). Compared to the commercial Fe/Cr catalyst, which exhibits 37.8 % at 350 °C, the activity of the catalyst E is significantly higher. None or very low concentrations of hydrocarbons were produced, implying that the catalyst is selective towards the desired products, H2 and CO2. The other prepared catalysts, Pt/Re/CeZrO2 and Pt/Re/TiO2, performed poorly in terms of selectivity. Pt/Re/CeZrO2 produced as much as 5.97 % methane at 450 °C. The Pt/Re/TiO2 catalyst produced 0.16 % methane at 450 °C. Because of the methane formation, it was concluded that the Pt/Re/CeZrO2 and Pt/Re/TiO2 catalyst formulations are not suitable for HT WGS applications, and were therefore not further studied in the long-term stability test.
The long-term stability tests were performed on the catalyst E. No deactivation signs were noted during the 135 hours on-stream and reactor temperature at 400 °C. The thesis project presents successful results from the experiments performed on the developed chromium-free catalyst for HT WGS applications. In terms of the activity and selectivity, it is concluded that catalyst E exceeds the performance of a commercial Fe/Cr catalyst. Stability results show that the catalyst is stable for at least 135 hours, not indicating any deactivation signs.}},
author = {{Grikainyte, Milda}},
language = {{eng}},
note = {{Student Paper}},
title = {{Improvement of Pt-based catalyst supported on CeZrO2 used for the high-temperature water-gas shift reaction}},
year = {{2022}},
}