Transcript Document

Life Cycle Inventory of Methyl Methacrylate
Yong Li, Evan Griffing, Celia Ponder, Michael Overcash
Department of Chemical & Biomolecular Engineering
North Carolina State University, Raleigh, NC 27695
"A hundred years after we are gone and forgotten,
those who never heard of us will be living with the
results of our actions."
--Oliver Wendell Homes
4d (l)
99 oC
Agitator 1
1 (l)
968 kg Acetone cyanohydrin
25.0 oC
5 (s)
90 oC
2 (l)
25 oC
P1
Summary of LCI information
Fugitive Losses makeup (Total) (g)
10.2 kg Methyl methacrylate
3.33 kg Methanol
2.43 kg Ammonia
1.14 kg Acetone
0.0479 kg Dimethyl ether
25 oC
D
Input
7 (l)
140 oC
CAS
P4
Chemical
75-86-5 Acetone cyanohydrin
7664-93-9 Sulfuric acid
67-56-1 Methanol
7664-41-7 Ammonia
Total
Cracker
R2
R1
T: 140 oC
Hydrolysis reactor
T: 90 oC
S1
S2
C17
C18
8 (l)
140 oC
C5
14 (l)
60 oC
7 atm
A
C3
13 (l)
125 oC
7 atm
HX 2
Amount Purity (%) Units
968
[kg/1000kg product]
2125
97.6 [kg/1000kg product]
336
[kg/1000kg product]
587
[kg/1000kg product]
4016
[kg/1000kg product]
10 (l)
125 oC
7 atm
9 (l)
125 oC
P5
HX 1
Non-reacting input
C6
Abstract
Among many methacrylic monomers, methyl methacrylate (MMA) is the
most important. Application of MMA is mainly in construction/remodeling
activity, automotive applications and original equipment manufacture. World
consumption of methyl methacrylate was about 2.5 million metric tons in 2005, The
methacrylamide sulfate route has dominated the commercial production of MMA
since 1934. In this study, design-based approach methodology is used to obtain life
cycle inventory data of MMA manufacturing process.
C4
22 (l)
59.4 oC
23 (l)
59.4 oC
12 (l)
25 oC
7atm
R3
B
11 (l)
470 kg Water
333 kg Methanol
25.0 oC
P8
Ester reactor
T: 125 oC
P: 7 atm
S3
CAS
Chemical
7732-18-5 Water
Total
P6
S4
24 (l)
60 oC
A
Trb 2
Purity (%)
Units
[kg/1000kg product]
[kg/1000kg product]
1270
1270
Benign outflows
25 (l)
60 oC
14 (l)
60 oC
7atm
Amount
Room cooling
24a (l)
60 oC
CAS
Chemical
7732-18-5 Water
Total
Flash column
Decanter 1
26 (l)
57.0 kg Acetone
2.39 kg Dimethyl ether
0.0187 kg Methanol
25.0 oC
16 (l)
60 oC
27 (l)
60 oC
Trb 1
Amount
Purity (%)
1297
1297
Units
[kg/1000kg product]
[kg/1000kg product]
Chemical emissions
P10
P11
27a (l)
60 oC
Design-Based Methodology
17 (l)
60 oC
Acid stripper
22 (l)
59.4 oC
Wash column
(Mx 2)
P13
20 (l)
60 oC
P7
D
31 (l)
48.4 oC
B
30 (l)
48.4 oC
P12
Mx 1
C6c
C6
C5
33b (l)
25 oC
3.4 atm
33a (l)
138.5 oC
3.4 atm
HX 3
33c (l)
13.9 kg
Water
10.1 kg
Methyl
methacryl
ate
25.0 oC
Trb 3
Di 2 Dehydration column
T: 138.5 oC
P: 3.4 atm
C
C6d
33d (l)
138.5 oC
3.4 atm
C9
C8
C7
35 (l)
100 oC
HX 5
34 (l)
100 oC
33f (l)
30 oC
Di 3 T: 100 oC
P14
C10
Trb 4
C6e
33e (l)
30 oC
3.4 atm
37 (l)
100 oC
S7
S8
HX 4
Room cooling
Process Design
36 (l)
998 kg Methyl methacrylate
1.53 kg Water
0.0439 kg Methacrylic acid
25.0 oC
C6f
38 (l)
44.2 kg Formamide
4.34 kg Methacrylic acid
1.50 kg Methyl methacrylate
0.0185 kg Methanol
0.0155 kg Water
25.0 oC
D
39 (g)
485 kg Ammonia
25.0 oC
20 (l)
60 oC
C13
R4
43 (l)
25 oC
44 (l)
1128 kg Water
41.7 kg Ammonia
9.18 kg Methyl methacrylate
25.0 oC
HX 6
C12
C11
42 (l)
100 oC
40 (l)
56.2 oC
P16
C14
21.8
57.0
44.2
2.43
41.7
17.1
170
-10
[kg/1000kg product]
[kg/1000kg product]
[kg/1000kg product]
0 [kg/1000kg product]
[kg/1000kg product]
Amount Units Comments
61.2 [MJ/hr]
0 [MJ/hr]
[MJ/hr] 85% efficiency has been included to determine
how much steam is needed for heating process
6294
fluid
Direct fuel use in high
0 [MJ/hr]
temperature heating
Heating natural gas
0 [MJ/hr]
Energy input
[MJ/hr] Electricity + steam + direct fuel oil + Dowtherm
requirement
6355
Cooling water
-4480 [MJ/hr]
Cooling refrigeration
0 [MJ/hr]
Potential Heat
[MJ/hr]
Recovery
-1121
Net energy
[MJ/hr] Energy input requirement minus potential heat
5234
recovery from cooling systems.
C15
6,000
P15
48 (l)
124 kg Water
1.02 kg Methyl methacrylate
25.0 oC
HX 7
S9
S10
5,000
C16
47 (g)
100 oC
4,000
45 (l)
99 oC
50 (l)
o
C
46 (l)
99 oC
Room cooling
Dry 1
Agitator 1
Pump 17
Evaporator 1
Pump 16
Pump 15
Vacuum pump 1
Pump 14
Pump 13
Pump 12
Pump 11
Pump 10
Pump 8
Pump 7
Pump 6
Pump 5
Dryer 1
Potential recovery
Di 1
Distillation reboiler 3
Room cooling
Reactor 3
4b (l)
30.6 kg Water
25.0 oC
Reactor 1
C2
4a (l)
99 oC
P2
0
Distillation reboiler 2
3 (l)
2074 kg Sulfuric acid
51.0 kg Water
25.0 oC
1,000
Pump 3
S11
2,000
Distillation reboiler 1
51 (l)
2794 kg Ammonium sulfate
S12 11.3 kg methyl alpha-hydroxyisobutyrate
4.43 kg Methacrylic acid
1.25 kg Water
9.67E-03 kg Acetone cyanohydrin
1.56E-13 kg Propanamide, 2-methyl2(sulfooxy)-, sulfate(1:1)
25.0 oC
Pump 2
P17
C1
3,000
Pump 1
Fugitive Losses (Total) (g)
10.2 kg Methyl methacrylate
3.33 kg Methanol
2.43 kg Ammonia
1.14 kg Acetone
0.0479 kg Dimethyl ether
25 oC
Process Unit
4 (l)
25 oC
4c (l)
99 oC
4d (l)
99 oC
S1a
S1b
D
P3
.Methacrylic acid and derivatives, Ullmann's Encyclopedia of Industrial Chemistry, 2005 online version, Wiley-VCH Verlag GmbH&Co.KGaA.
2. Methacrylic acid and derivatives, Kirk-Othmer Encyclopedia of Chemical Technology, Vol 16, pp227-270, John Wiley & Sons.
10.2
1.14
[kg/1000kg product]
[kg/1000kg product]
[kg/1000kg product]
[kg/1000kg product]
Cumulative Energy Input
Evaporator 1
41 (l)
56.2 oC
67-56-1 Methanol
115-10-6 Dimethyl ether
79-41-4 Methacrylic acid
80-62-6 Methyl
methacrylate
67-64-1 Acetone
75-12-7 Formamide
7664-41-7 Ammonia
Total
Mass Balance Difference
Units
Source
Electricity
Dowtherm
Heating steam
Vacuum pump 1
S6b
Amount
Gas
Liquid Solid
3.33 0.0371
0.0479
2.39
4.34
Energy Use
S6a
Capital equipment of the manufacturing process is not included, such as
construction of the plant and decommissioning.
Waste treatment module is not included in this study.
All inputs and outputs leave at 25 C and atmospheric pressure, and a basis
of 1000 kilogram per hour final product is used.
97.6% sulfuric acid is further purified to 99% before pumped to the reactor 1.
The acetone cyanohydrin and sulfuric acid in reactor 1 have a mole ratio of 1:1.86,
and the reactor is operated at 90oC, and 1 atm1. The sulfuric acid serves both as a
specific reactant and as a solvent for the reaction, which appears to involve an αsulfatoamide intermediate. After the initial reaction, the mixture is subjected to brief
thermal cracking at 140 oC to convert most of the α-hydroxyisobutyramide
byproduct to methacrylamide sulfate. In general, for this stage, the acetone
cyanohydrin conversion is typically 100% with selectivity about 90-95% to
methacrylamide sulfate2.
In the next stage, sulfuric acid serves as catalyst in a combined
hydrolysis/esterification of the methacrylamide sulfate to a mixture of methyl
methacrylic acid and methyl methacrylate. Ammonium bisulfate is formed as a
coproduct at equimolar amounts to the amount of methacrylate formed. The
esterification is carried out at 140 oC and 7 atm2.Some of the by-products from this
stage include dimethyl ether, methyl α-hydroxy-isobutyrate etc. The reactor effluent
is separated using a decanter. The lower layer is steam stripped to recover
methacrylic acid for recycling to the hydrolysis-esterification stage. The waste
ammonium acid-sulfate from the steam stripping step is treated with ammonia to
produce fertilizer ammonium sulfate. The upper layer passes through a flash to
remove low boiling components such as dimethyl ether and acetone, and a
dehydration column to remove water. The product is then purified through a
distillation column.
C
Chemical
Start
•
•
18 (g)
500 kg Water
101.0 oC
19 (l)
60 oC
33 (l)
48.4 oC
3.4 atm
•
33 (l)
48.4 oC
32 (l)
48.4 oC
the utilities and emissions after waste management are not included.
Assumptions
29 (l)
25 oC
MJ / hr
In this study, we use design-based approach methodology to obtain most of
the life cycle inventory data, in which the life cycle information of MMA
production is obtained using chemical engineering design techniques. The
functional unit is defined as 1000 kg MMA product.In an effort to be more
transparent and reflect the main process variables, the energy values and
chemical losses are for the actual manufacturing processes. Energy to generate
21 (g)
99 oC
CAS
28 (l)
300 kg Water
100 kg Ammonia
25.0 oC
Process Flow Diagram of The Methacrylamide Sulfate Route
Conclusion
1. About 3 tons of ammonium sulfate will be generated for every ton of MMA
production. Therefore, allocation will be need to use this LCI data.
2. Major energy source consumed in this process is steam energy. Evaporator and
reactor 3 consume the most energy in the process.