*Dipl.-Ing. Florian Rau

TU Bergakademie Freiberg | Institute of Thermal Engineering | Chair of Gas and Heat Technology | Gustav-Zeuner-Str. 7 | 09599 Freiberg | Germany

Phone: +49 3731 39 3013 | Fax: +49 3731 39 3942 I florian.rau@iwtt.tu-freiberg.de | www.gwa.tu-freiberg.de

PRODUCTION OF HYDROGEN BY AUTOTHERMAL REFORMING OF BIOGAS

Florian Raua,*, Andreas Herrmanna, Hartmut Krausea, Debora Finob, Dimosthenis Trimisc

The enhanced efforts in the decarbonisation of the transport sector is a strategy of the European Union to reduce the anthropogenic part of climate change. Therefore,

several ways for the powertrains of the future have been developed with fuel cells as a promising option. In order to support the strategy, the scope of the project BioRobur

(Biogas robust processing with combined catalytic reformer and trap), funded by the European Commission, is the decentralized production of hydrogen for an on-site

supply for gas stations. With the aim of keeping the environmental impact as low as possible, biogas is used as educt for the reforming instead of natural gas.

The investigations of the boundary conditions for an autothermal reforming of biogas to a hydrogen rich gas at a pilot-plant with a hydrogen production of 50 Nm³/h are

summarized. The focus is the long-term behavior of the novel Nickel-based catalyst. This includes the investigation of the impact of the start-up sequence on the reforming

performance after the necessary activation of the catalyst. Additionally the time for cold and warm start of the pilot-plant have been measured and optimized.

The pilot-plant takes the educt pretreatment and the autothermal reforming into account, while the steps of hydrogen purification are skipped.

The team of the TU Freiberg would like to thank the European commission for the financial support of this work in the Seventh Framework Programme project BioRobur

under grant agreement n° 325383.

Introduction

Experimental setup

Impressions of the pilot-plant

Acknowledgements

Figure 1 - Block flow diagram of the pilot-plant of the project BioRobur

aTU Bergakademie Freiberg, Institute of Thermal Engineering, Freiberg, GermanybPolitecnico di Torino, Department of Applied Science and Technology, Torino, Italy

cKarlsruhe Institute of Technology, Engler-Bunte-Institute, Division of Combustion Technology, Karlsruhe, Germany

Figure 6 - Synthetic gas composition (left) and analysis (right) of the long-term test of the Ni-based catalyst at

GHSV = 4,000 1/h, O/C = 1.1, S/C = 2.0 with two different inlet temperatures

The decentralized production of hydrogen with a Nickel-catalyst as well as with a noble metal catalyst has been successfully investigated. The Nickel-catalyst showed

promising results during the long-term test. The omission of a reliable hydrogen source, of the activation procedure and of the deactivation as well as lower start

temperatures are very important advantages of a noble metal catalyst. So the deciding fact will be the economical part.

The pilot-plant showed already a high plant efficiency of 68% at a low level of heat integration. Improvements up to the level of the cold gas efficiency (90%) are possible.

Therefore three additional heat exchangers are required.

Summary

Results of the start-up sequence and the reforming start-up time

Results of the long-term test of the Ni-based catalyst

Figure 3 - Reforming start-up time, cold start (left) and warm start (right) for the noble metal catalyst

Figure 2 – Overview (left) and results (right) of the most reliable start-up sequences

Legend

Green flow controller

Blue pressure

Red temperature

Yellow safety

Project catalyst: Ni (5 wt.-%) / Rh (0.05 wt. %) on MgAl2O4 spinel

Long-term test at 40% load

Accumulated test time is 52 hours (only reforming time; time for heat-up and

activation is not considered).

Hydrogen yield, methane conversion as well as cold gas efficiency show

differences between each run but minor degradation during steady operation

Methanation after soot trap visible

Degradation during start-up unavoidable. Main indicator for degradation is

amount of methane in the synthetic gas directly after the catalyst. (Purple line at

left side of Figure 6)

Figure 4 - Overview of the plant (left) and ATR reactor and steam super heater without insulation (right)

Figure 5 - Noble metal catalyst as monolith (left), Ni-based catalyst as foam (middle), Fe-based Soot Trap as monolith (right)

The second start-up sequence shows the best results in terms of cold gas

efficiency, methane conversion and hydrogen yield.

The reforming start-up time for a cold start is 2:35 h and for a warm start 0:40 h.