Hydrogen Production via Biogas Reforming over

Chemical Process Engineering Research Institute

Technological Educational Institute of Western Macedonia Laboratory of Alternative Fuels & Environmental Catalysis

Hydrogen Production via Biogas Reforming over Nickel-Alumina Catalysts. Effect of Catalysts’ Synthesis Method

M.A. Goula, O.A. Bereketidou, N.D. Charisiou, K.N. Papageridis, E. Pachatouridou, E.F. Iliopoulou


H2:

Introduction

• is a clean energy carrier • is expected to be one of the main energy sources in the 21st century

Biogas: • is a clean & environment friendly fuel • is generated typically from anaerobic degradation of biomass • Raw biogas basically contains: ~ 55-65% CH4 ~ 30-45% CO2

Biogas Reforming • is essentially CO2 reforming or dry reforming of CH4 • addition of a reforming catalyst enhances the yield to H2 or the production of syngas

CH4 & CO2 are: • main greenhouse gases • it can be converted into H2 or Synthesis Gas (syngas) via..

Hydrogen Production via Biogas Reforming over Nickel-Alumina Catalysts. Effect of Catalysts’ Synthesis Method Aim of Present Study  Evaluation of catalysts in biogas reforming reaction  Investigation of the effect of catalysts’ preparation method on their structure & catalytic activity

Catalytic Materials  8% Ni/ Al2O3 - Dry Impregnation  8% Ni/ Al2O3 - Wet Impregnation  8% Ni/ Al2O3 - EDF Method

[Labeled herein as 8Ni/ Al-dry] [Labeled herein as 8Ni/ Al-wet] [Labeled herein as 8Ni/ Al-edf]

Catalyst Characterization & Evaluation  X-Ray Diffraction (XRD): Identification-evaluation of Ni-phases & catalysts crystallinity  Temperature Programmed Reduction (TPR-H2): Investigation of the reducibility of the fresh catalysts & examination of the strength of Ni species interaction with the Al2O3 surface  Biogas Reforming Reaction: Evaluation of catalysts activity in % conversion of CH4 & % yields of H2

Hydrogen Production via Biogas Reforming over Nickel-Alumina Catalysts. Effect of Catalysts’ Synthesis Method Catalysts Preparation • Support: Commercial γ-Al2O3 (AKZO, 350-500 μm, SBET= 195 m2/g • Precursor salt of Ni: Ni(NO3)3·6H2O • Preparation Methods: 8Ni/ Al-dry: Dry Impregnation Method 8Ni/ Al-wet: Wet Impregnation Method

8Ni/ Al-edf: Equilibrium Deposition Filtration Method (pH=7) • All the samples were dried at 120°C for 3 hrs & calcined at 800°C for 5 hrs • Prior reaction, the catalysts were reduced in H2 flow at 700 or 800°C for 1 hr


Characterization Results

TPR-H2 H2

FI

O2

XRD

He

FI

MS

VENT

 Catalyst weight: ~100 mg  Quartz fixed bed reactor  Pre-treatment Step: RT → 600°C (3°C/min) with He (50cc/min) for 1 hr  Reduction Step: RT → 900°C (10°C/min) with 5% H2/ He (50cc/min)  The outlet gases were analyzed by a Mass Spectrometer)

Hydrogen Production via Biogas Reforming over Nickel-Alumina Catalysts. Effect of Catalysts’ Synthesis Method XRD: Identification-evaluation of Ni-phases & catalysts crystallinity

 Characteristics peaks of γ-Al2O3: 2θ= 37°, 45.9° & 67°

 Spinel NiAl2O4 phase peaks: 2θ= 19°, 31° & 59.8°  NiO phase: not detected, probably due to the small size of crystallite

Hydrogen Production via Biogas Reforming over Nickel-Alumina Catalysts. Effect of Catalysts’ Synthesis Method TPR-H2: Investigation of the reducibility of the fresh catalysts & examination of the strength of Ni species interaction with the Al2O3 surface

 Two main peaks are observed for all the samples: 280-365°C NiO reduction 650-750°C NiAl2O4 reduction

 In the case of 8Ni/ Al-edf sample, the NiAl2O4 phase peak is shifted to the lowest temperature (650°C)


Evaluation Results: Biogas Reforming Reaction

 Catalyst weight: ~50 mg  Fixed bed reactor  Temperature range: 550-850°C  Gas mixture: CH4/ CO2/ He (100cc/min)  GHSV: 120000 ml·g-1·h-1  Gaseous reaction products were analyzed on-line by Gas Chromatography

Hydrogen Production via Biogas Reforming over Nickel-Alumina Catalysts. Effect of Catalysts’ Synthesis Method Biogas Reforming Reaction: Evaluation of catalysts activity in % conversion of CH4 & % yields of H2

 The catalytic activity increases with temperature.  The pretreatment at 800°C significantly enhances the catalytic performance for all the catalytic samples.  At the range of 750-850°C, H2 yield values are higher for 8Ni/ Al-edf catalyst compared to 8Ni/ Al-dry & wet catalysts (after reduction at 800°C).

Hydrogen Production via Biogas Reforming over Nickel-Alumina Catalysts. Effect of Catalysts’ Synthesis Method Conclusions  XRD patterns of all three catalysts reveal the presence of NiAl2O4 phase.  TPR-H2 profiles present that edf sample has more efficient reducibility of Ni-phases on the catalyst (Treduction of NiAl2O4~650°C).

 The preparation method affect the catalytic properties of Ni-based on Al2O3 catalysts.  The catalytic activity increases with temperature, while pre-reduction at 800°C significantly enhances the catalytic performance, possibly due to the reduction of the undesired NiAl 2O4 phase.  8Ni/ Al-edf catalyst, pre-reduced at 800°C is relative more active in the reforming reaction for temperature values above 750°C.

Chemical Process Engineering Research Institute

Technological Educational Institute of Western Macedonia Laboratory of Alternative Fuels & Environmental Catalysis

Thank you very much for your attention! M.A. Goula*, O.A. Bereketidou, N.D. Charisiou, K.N. Papageridis, E. Pachatouridou**, E.F. Iliopoulou

*e-mail: [email protected] **e-mail: [email protected]