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Advance Catalysis Chemistry

Synthesis of Fe/MgO nano-crystal

catalysts by solgel method for hydrogen

sulfide removal

Vu Anh Tuan ID: 2011323066

Department: Chemical and Biomolecular Engineering

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Introduction

1. Raw biogas contains: 5580% methane (CH4) and 2045% carbon

dioxide (CO2) with small amounts of water vapor, trace amount of

hydrogen sulfide (01% H2S), and other impurities.

2. alkaline/amine scrubbing, chemical oxidation, adsorption, bio filtration,

and catalytic wet oxidation.

3. The mechanism of H2S oxidation on Fe/MgO

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Introduction

4. Method synthesis MgO: solgel, hydrothermal, flame

spray pyrolysis, laser vaporization, chemical gas phase

deposition and surfactant methods.

5. Fe/MgO nano-crystal catalysts were then prepared by

wet impregnation.

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Result and discussion

MgO catalyst support media

1. Effects of calcination temperatures on MgO synthesis

Fig. 3d. This diffraction pattern agreeswell with the peaks of standard MgO.This confirms that MgO was formed tohigh purity from the synthesis. Thisresult also shows that the crystalsmatch with the lattice parameters: a =4.2198 , b = 4.2198 , c = 4.2198 , =90.0000 , = 90.0000 , = 90.0000 and

Z = 4.00.

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Results and discussion

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Result and discussion

2. Effects of precursor molar ratios on the MgO crystal size

The crystal size of MgO (d, nm) was calculated from the (2 0 0)

diffraction peak using the well-known Scherrer equation.

K is a dimensionless constant that may range from 0.89 to

1.39 depending on the specific geometry of the scattering objects

and B variables are the angles between the incident and

diffracted beams () and the full width at half maximum,

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Results and discussion

(c) BET surface areaand the pore volumewere 178.46m2/g and0.00311 ml/g

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Result and discussion

Characterization of the Fe/MgO catalysts

From the XRD data,the

Fe/MgO nano-crystal size

was calculated to be 17.5 nm.

From the BET analysis,

the BET surface area and

the pore volume were

171.59m2/g and 0.00298 ml/g

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Result and discussion

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Results and discussion

Catalytic activity in H2S oxidation.

1. H2S oxidation in a semi-batch reactor.

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Result and discussion

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Result and discussion

Characterization of the fresh and spent catalysts for H2Sdegradation

The fresh catalyst and the catalyst with regeneration samples had

the same brown color, while the spent catalyst without regenerationhad some black spots on the surface. The EDX characteristic results

showed 3 elements consisting of Fe, O, and Mg on the fresh and spent

catalysts with regeneration. In contrast, 4 elements consisting of S, Fe,

O, and Mg were found in the spent catalysts without regeneration.

The appearance of the S element can be determined from the

FTIR results provided in Fig. 9.

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Results and discussion

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Results and discusion

H2S absorption in packed column1. Effects of catalyst concentration on

the removal of H2S from biogas

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Results and discussion

2. Effect of L/G ratios on the H2S removal from biogas

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Results and discussion

3. The regeneration of the catalysts.

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Conclusion

1. The Fe/MgOnano-crystal catalysts were synthesized by a solgel

method. MgO nano-crystals with the sizes ranging from 12.9 to

36.3nm Fe3+ from ferric nitrate solution was supported on the MgO

nano-crystals by a wet impregnation technique to give 17.5nm

Fe/MgO crystals

2. The H2S removal from a biogas in a packed column scrubber using

the Fe/MgO nano-crystal catalysts with a sufficient air flow rate and

L/G ratio for the catalyst regeneration shows an outstanding

possibility. In addition, the reaction of the catalysts with methane was

not observed.

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