This presentation was done in June 2014 by one of our participants in ICST and ICBELSH conferences.

1. Formaldehyde synthetic simulation
of a fixed bed reactor over silver
catalyst
SUKUNYA ARREEYAH
Department of Chemical Engineering, Faculty of Engineering
Chulalongkorn University, Bangkok, Thailand
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2. The whole world, formaldehyde production amounts 32.5 million
tons per year in 2012. While demand increase similarly due to:
a) The versatility of formaldehyde which is intermediate in chemical
synthesis such as the many resin product.
b) The property improvement
c) Formaldehyde solution preserves tissue or cells
INTRODUCTION (1)
2

3. The generally formaldehyde process has 2 process:
1) The air deficiency process or silver contact process, passing
methanol over silver catalyst in fixed-bed reactor at
temperature 873-923 K.
2) The air excess or formox process , passing methanol over iron-
molybdenum-vanadium oxide or metal oxide catalyst in
multitubular reactor under 573-673 K.
INTRODUCTION (2)
3

4. The silver contact process including.:
1) The methanol ballast process, conversion of this process isn’t
complete.
2) The water ballast process , conversion and selectivity are
higher than methanol ballast process. The water ballast process
is additional steam in feed for preventing deactivation catalyst
so catalyst’s cycle duration is longer than methanol ballast
process
INTRODUCTION (3)
4

5. INTRODUCTION (4)
The feed streams (air, methanol, and water) pass through
adiabatic fixed-bed reactor under atmospheric pressure and 873-
923 K
5

6. INTRODUCTION (5)
(1)
(2)
(3)
(4)
(5)
6

7. • The component balance
(6)
• The energy balance
(7)
The fixed-bed reactor model
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8. The kinetic model (1)
Equation (8)-(9) shows totally reaction occurrence.
(8)
(9)
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9. The kinetic model (2)
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10. The kinetic model of slow steps show in Eq. (10)-(11), which refers
work of A. Andreasen et al.
(10)
(11)
The kinetic model (4)
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11. Results and discussion (1)
the formaldehyde and carbon dioxide synthetic simulations compare to
literature data in [8]
14
548 K 948 K 995 K

12. Results and discussion (3)
Simulation (formaldehyde yield (%)) plots against literature data in [8]
15

13. Results and discussion (5)
yield of formaldehyde which is provided by parameters in [8] compares
with increase and decrease 20% by mole of water feed.
16
0
10
20
30
40
50
60
70
80
90
50 55 60 65 70 75 80 85 90 95
yield(%)
Time (min)
yield of formaldehyde
-20% of water feed
+20% of water feed
84
Additional water in feed

14. Results and discussion (6)
Temperature in reactor which is provided by parameters in [10] compares
with increase and decrease 20% by mole of water feed. 17
Additional water in feed

15. Conclusion
The models are used to provide accurate dynamic behavior for the
oxidation reaction of methanol and formaldehyde throughout the
reactor length. The results of this work show as follows:
a) The models give good prediction of the formaldehyde yield,
especially at the reaction temperature between 500-975 K.
b) It was found that higher yield of formaldehyde can be achieved
by increasing the amount of water in feed.
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