Table of Contents

CHAPTER 1......................................................................................................2INTRODUCTION..............................................................................................2

1.1 Introduction..........................................................................................21.2 Physical properties.................................................................................21.3 Chemical properties...............................................................................31.4 Supply and Demand...............................................................................41.5 Production Technologies........................................................................6

CHAPTER 2....................................................................................................11MATERIAL AND ENERGY BALANCE...........................................................11

2.1 Introduction.........................................................................................112.2 Block Flow Diagram............................................................................112.3 Material Balance..................................................................................122.4 Energy Balance...................................................................................16

CHAPTER 3....................................................................................................20REACTOR SIZING CONSIDERING MAIN REACTION...................................20

3.1 Reactor Sizing According Algorithm.....................................................203.2 Catalyst Determination.........................................................................233.3 POLYMATH Result............................................................................24

REFERENCES.................................................................................................28

CHAPTER 1

INTRODUCTION

1.1 Introduction

Ethylbenzene is an organic compound with the formula (C6H5CH2CH3) also

known as phenylethane, ethylbenzl or alpha-methyltoluene, a single ring and alkyl

aromatic compound. In petrochemical industry, the aromatic hydrocarbon is important

and almost exclusively (> 90%) as an intermediate in the production of styrene, which

is used for making polystyrene, it is a common plastic material. In styrene production,

which uses ethylbenzene as a starting raw material, consumes ca. 50% of the world’s

benzene production. Less than 1% of the ethylbenzene produced is used as paint

solvent or as an intermediate for the production of diethylbenzene and acetophenone.

(Ullmman''s, 1985)

It is used as a solvent for aluminium bromide in anhydrous electro deposition

of aluminium. Ethylbenzene is an ingredient in some paints and solvent grade xylene

is nearly always contaminated with a few per cent of ethylbenzene. (Vincent

AVincent A.Welch, 2005)

Essentially all commercial of ethylbenzene production is captive consumed for

the manufacture of styrene monomer. Styrene is used in the production of polystyrene

and a wide variety of other plastics. Of the minor uses, the most significant is in the

paint industry as a solvent, which accounts for <1% of production capacity.

Acetophenone, diethylbenzene, and ethylanthraquinone with smaller volumes also go

toward for the production. (Vincent AVincent A.Welch, 2005)

1.2 Physical properties

Under ordinary conditions, ethylbenzene is a clear, colourless liquid with a

characteristic aromatic odour which can be detected at low concentrations.

Ethylbenzene is an irritant to the skin and eyes. Moreover, it is moderately toxic by

ingestion, respiratory effects such as throat irritation and lung constriction, irritation

to the eyes and skin adsorption. The physical properties of ethylbenzene are as

follows (Ullmman''s, 1985) :

Table 1.1: Physical properties of Ethylbenzene

No. Properties

1 Density

At 150C 0.87139 g/cm3

At 200C 0.8669 g/cm3

At 250C 0.86262 g/cm3

2 Melting Point -94.9490C3 Boiling Point At 101.3 KPa 136.1860C

4 Refractive IndexAt 200C 1.49588At 250C 1.49320

5 Critical Pressure 3609 KPa6 Critical Temperature 344.020C7 Flash Point 150C8 Auto Ignition Temperature 4600C

9 Flammability Limitlower 1.0%upper -

10 Latent Heatfusion 86.3 J/gm

vapour ization 335 J/gm

11 Heating Valuegross 429999 J/gmnet 40928 J/gm

12 Kinematic viscosityAt 37.80C 0.6428x10-6 m2/sAt98.90C 0.390x10-6 m2/s

13 Surface tension 28.48 mN/m

14 Specific Heat CapacityIdeal gas,250C 1169 J kg-1 K-1

Liquid,250C 1752 J kg-1 K-1

1.3 Chemical properties

Chemically, it is a monocyclic alkylaromatic compound with a 106 of

molecular weight. It is miscible with most of the commonly used organic solvents in

any ratio, but is only sparingly soluble in water (170 ppm under ambient conditions).

Spilled ethylbenzene will float on water and partition strongly towards air. No

significant environmental hazards are expected due to its high evaporation rate.

Being rather volatile and having a flash point of 19-23 °C, ethylbenzene is

classified as a highly flammable substance, which in use may form flammable or

explosive vapour-air mixtures. The most important commercial reaction of

Ethylbenzene is its dehydrogenation to styrene. The reaction is carried out at high

temperature (600-6600C) usually over an iron oxide catalyst. Steam is used as

diluents. Commercially, selectivity’s to styrene range from 89 to 96% with per-pass

conversions of 65-70%.

The production by products is reduced if the temperature is gradually lowered

during the course of the reaction. The hydro peroxide is subsequently reacted with

propene in a process that yields styrene and propylene oxide as co products. With

suitable catalyst, it can be converted to xylenes. Commercially processes for

isomerising xylenes usually involve the catalytic isomerisation or dealkylkylation of

Ethylbenzene. Like toluene, it may be dealkylated catalytically or thermally to

benzene. It is also undergoes other reaction typical of alkyl aromatic compounds.

(Vincent AVincent A.Welch, 2005)

1.4 Supply and Demand

We have mentioned that ethyl benzene is a colourless liquid with a gasoline

odor and high inflammability. So that it is widely used in the petrochemical industry

in manufacturing of styrene.

Styrene is used mostly important applications of ethylbenzene that were

manufactured in polymer production for polystryrene and mostly in polymer

production for polystyrene, acrylonitrile-butadiene-styrene (ABS) and styrene-

acrylonitrile (SAN) resins, styrene-butadiene elastomers and latexes, and unsaturated

polyester resins..

It is also used as an intermediate material in the production of plastic products

and is utilized as one of the basic raw materials in the production of various

chemicals. Ethylbenzene also a good solvent which it have in different sectors like in

the rubber industry, ink industry, the major markets of the styrene ware include

packaging, electrical/electronic/appliances, construction and consumer products.

The global demand for ethyl benzene is growing wherein the Asia Pacific

region has retained more than 47% of the market. China is the largest consumer and

producer of ethyl benzene, having a market share of 28%. It is because, the value of

Ethyl Benzene were so high that will give benefit to the industry to produce more

product that were linked to Ethyl Benzene.

This shows that the Ethyl Benzene (EB) is quite an important chemical

product that has a lot of uses to the industry. Based on analysis, The Asia-Pacific is

the biggest market of benzene consuming a significant share of the total consumption

in 2012, and it is also the second fastest growing market next to ROW. The

consumption patterns of benzene and its various derivatives are continuously showing

an upward trend which is mainly due to the shift of manufacturing industry to the

Asia-Pacific on account of increasing demand and low cost of production. China is

the leading country in the region in terms of both, production as well as consumption

of benzene and its derivatives, while the Indian market, despite being small in size, is

expected to be a market with high potential (PRNewswire , New York, June 19,

2014).

Figure 1. 1: The consumption of Ethyl benzene in the world in 2013

Figure 1.1 shows the consumption of Ethyl benzene in the world in 2013. The

world consume the EB about 99% to produce a lot of variety product that will

generate economy and about 1% consumed of ethylbenzene is used for other

applications.

For instance, global demand for ethyl benzene amounted to 28,567,852 tons

in 2014 (BGI research, 2012). The global EB market was dominated by the Asia-

Pacific region, with the domestic markets in developing economies expanding

exponentially (Global Chemical Price, 2013). The increasing standard of living and

increased styrene capacities across the globe increased the usage of EB in a number of

countries. With demand recovery expected in developed markets and increasing

demand expected from developing economies, overall global EB demand is expected

to have reached 34,667,874 tons by 2020 (GBI Research, 2012). Figure 1.2 shows

global demand trends for EB in volume terms from 2000 to 2020.

Figure 1. 2: Global Demand Trends for EB in volume terms from 2000 to 2020 by GBI Research (2012)

1.5 Production Technologies

Currently, almost all ethylbenzene is produced commercially by alkylating

benzene with ethylene. There are different manufacturing processes available for

ethylbenzene .Some these are listed below:

1) Liquid phase aluminum chloride catalyst process

2) Vapour-phase zeolite catalyst process

3) Liquid phase zeolite catalyst process

4) Mixed Liquid-Vapour Phase zeolite Catalyst process

1.5.1 Liquid Phase Aluminium Chloride Catalyst Process

This is the first process used in producing of ethylbenzene since 1930’s.

Alkylation of benzene with in the presence of an aluminum chloride catalyst complex

is exothermic (_H-114 kJ/mol); the reaction is very fast and produces almost

stoichiometric yields of thyl benzene. In addition to AlCl3, a wide range of Lewis

acid catalysts, including AlBr3, FeCl3, and BF3, have been used. Aluminum chloride

processes generally use ethyl chloride or hydrogen chloride as a catalyst promoter.

These halide promoters reduce the amount of AlCl3 required.

1.5.2 Vapour-Phase Zeolite Catalyst Process

Vapour-phase alkylation has been practiced since the early 1940s, but at that

time processes were unable to compete with liquid-phase aluminum chloride based

technology. The alkar process developed by UOP, based on boron trifluoride catalyst,

had modest success in the 1960s, but fell from favour because of high maintenance

costs resulting from the severe corrosion caused by small quantities of water.

Nevertheless, some Ethylbenzene units continue to use this process. The Mobil –

badger Ethylbenzene process represents the latest and most successful vapour phase

technology to be introduced. The process was developed in the 1970’s around.

1.5.3 Liquid Phase Zeolite Catalyst Process

The EBMax process offered by Mobil/badger is a liquid phase alkylation

reaction using a catalyst based on the MCM-22. A commercial plant based on the

EBMax technology was commissioned in 1955 at Chiba Styrene Monomer Company.

1.5.4 Mixed Liquid-Vapour Phase zeolite Catalyst process

The CDTECH process is based on mixed liquid-vapour phase alkylation reactor section. The design of commercial plant is similar to the

liquid phase technologies except for the design of the alkylation reactor which combines catalytic reaction with distillation into a single

operation.

Table 1.2: The Comparison for Production Technology of Ethylbenzene. (Shenglin Liu, March 2009)

PropertiesLiquid Phase Aluminium Chloride Alkylation

Vapour-phase Zeolite Alkylation

Liquid phase Zeolite Alkylation

Mixed Liquid-vapour phase Zeolite Alkylation

Operating Temperature

400-450 C 450° to 600° C.

Operating Pressure

2-3 MPa (20-30 bars).

Conversion 99% 100% 100% 100%

Phase

Three phase are present ; Aromatic liquid, ethylene gas, and a liquid catalyst complex phase

The high-activity catalyst allows transalkylation and alkylation to occur simultaneously in a single reactor

The alkylation reactor is maintained in liquid phase

Mixed liquid-vapour phase

CatalystAluminium Chloride catalyst complex

Zeolite Catalyst Zeolite Catalyst Zeolite Catalyst

Advantages i. The aluminium chloride present in alkylation reactor effluent catalyst trans alkylation

i. Use of zeolite catalyst that eliminated issues associated with corrosion and waste disposal of aluminium chloride

i. The liquid phase zeolite catalyst process operates at substantially lower temperature decreased

i. Combines catalyst reaction with distillation into single operationii. The exothermic heat

reaction.ii. Reaction is very fast in presence of Aluminum chloride &produces almost stoichiometric yields of Ethylbenzene.iii. Essentially 100% of ethylene is converted

ii. The original vapour phase design accomplished the alkylation and trans alkylation reactions in single reactoriii. The third generation technology is capable of achieving EB yield greater than 99%iv. The third generation technology offered significant benefits in purity ,capital cost

side reactions dramatically resulting in ultra-high purity EB productii. The plant achieve high on stream efficiency often greater than 99% which results in low turnaround & maintenance costiii. EBZ-500 catalyst has operating length of more than 8year without catalyst regenerationiv. The regeneration is mild carbon burn procedure that is relatively inexpensive

of reaction creates vaporisation necessary to effect distillationiii. Capable of using dilute ethylene feed e.g. Off gas from a fluid catalytic cracking plant or dilute ethylene from steam crackeriv. In general ethylene feed streams containing significant amounts of hydrogen, methane or ethane do not require some pre-treatment. (David Netzer, 1999)

Disadvantages i. Handling and disposal of aluminium chloride catalyst and waste has become increasingly more costly and complicated because of environmental considerationsii. Equipment and piping corrosion and fouling along with related environmental issues led to development of EB

i. The significant extent of isomerisation reactions and catalyst deactivation by deposition of carbonaceous material are most important problems associated with high temperatureii. The length of time between regeneration can vary from as little as 2 months to slightly more than 1 year depending on specific plant design and operating conditions

Do not have disadvantage

process based on solid acid heterogeneous catalystsiii. Major equipment pieces needed to replace on regular schedule because of corrosion which results in extensive turnarounds poor plant on-stream efficiency and thus are primary contributors to the high operating costs associated with aluminium chloride

iii. Because the reactors must be taken off line for regeneration ,on-stream efficiency can be low resulting in high operating costs for vapour phase plantiv. Additional equipment may be required for regeneration procedure depending on specific plant design which adds capital cost to plant

From above advantages & disadvantages for different processes we select Vapour Phase Zeolite Catalyst process (UOP). Since it has

more advantages over other existing manufacturing process for Ethylbenzene. Not only that, it also have long catalyst run-length with excellent

stability which can minimizes plant downtime, and It has highly selective reaction that are insignificant amount of xylenes are produced,

providing a highest product quality. Also it requires less pure benzene & ethylene. Less harm full to environment also. (technology, 2012)

CHAPTER 2

MATERIAL AND ENERGY BALANCE

2.1 Introduction

This chapter will focus on calculation of material and energy balance for

production of 40,000 MT of Ethylbenzene. The reaction kinetics of EB production is

as follows. The production of ethylbenzene (C6H5C2H5) takes place with the direct

addition reaction between ethylene (C2H4) and benzene (C6H6).

C6H6 + C2H4 C6H5C2H5 ----- (1)

However, there is another inevitable reaction takes place at the same time as

reaction (1) which is to produce diethylbenzene (C6H4(C2H5)2), an unwanted product.

C6H5C2H5 + C2H4 C6H4(C2H5)2 ----- (2)

2.2 Block Flow Diagram

To roughly interpret the process of the Ethylbenzene production, an input-

output structure of reactor is illustrated as shown in Figure 2.1. In stream 1, there is

pure feed of Benzene, n1, and in stream 2, a pure feed of Ethylene, n2. Stream 3

consists of unconverted ethylene n3 and benzene n4, ethylbenzene n5, as well as

diethylbenzene n6.

Figure 2. 1: Input-output structure of reactor of Ethylbenzene plan

2.3 Material Balance

As this is mini project for Chemical Reaction Engineering II, we will consider

the material balance in the reactor only. Analysis of material balance follows the

extent of reaction method. The symbols ξ1 and ξ2 are used to denote the extents of

reaction for the first and second reaction, Equation (1) and Equation (2) respectively.

The material balances of all chemical species are generally computed using

the correlation as follows:

ṅi = ṅ0 + vi ξ1 -----(3)

where ṅi is molar flow rate of the species i and v i is the stoichiometric coefficient. The

summary of using extent of reaction is as in Table 2.1.

Table 2.1: Material Balance Summary

Species Inlet Change OutletBenzene FB - ξ1 0Ethylene FE - ξ1- ξ2 0

Ethylbenzene 0 ξ1- ξ2 PEB

Diethylbenzene 0 ξ2 PDEB

The capacity of the plant producing commercial grade ethylbenzene is 40,000

metric tonne per year and it has been assumed that the plant operates 8000 hours per

year with about 32 days for shutdown, maintenance and troubleshooting. The basis of

production of ethylbenzene per day will be used.

40,000 MTyear

x1000 kg

1 MTx

1 year8000 hours

=5000 kg /hours ----- (4)

From Equation (4), 5000 kg of Ethylbenzene will be produced per hour. The

assumption of calculation are listed as follows;

Pure benzene and ethylene

All gases behave ideally

Yield is 99.99%

90% conversion of ethylene (limiting reactant) to ethylbenzene &

diethylbenzene

Molecular mass for each species is summarized in Table 2.2

Table 2.2: Molecular Mass of Species Involved in the Process

Species Molecular Mass (kg/kmol)Ethylene 28.05Benzene 78.11

Ethylbenzene 106.17Diethylbenzene 134.22

Ethylene

Ethylene inlet into the reactor, FE = FFE + (1 - X)

= FFE/X

= PEB/YX

= 47.09/0.99 (0.9)

n2 = 52.85 kmol/hour

Ethylene outlet from the reactor, FE = FFE + (1-X)

= PEB/YX * (1-X)

= 47.09/0.99 (0.9) * (1-0.9)

n3 = 5.29 kmol/hour

Benzene

For PEB,

n5 = ζ = 5000 kg

hourx

1 kmol106.17 kg

= 47.09 kmol/hour

For benzene inlet into the reactor,

= PEB/Y+FE (3 – X)

= 47.09/0.99 + 52.85 (3-0.90)

n1 = 158.55 kmol/hour

Benzene outlet from the reactor,

= PEB/YX (3-X)

= 47.09/0.99(0.9) * (3-0.90)

n4 = 110.99 kmol/hour

Diethylbenzene

Diethylbenzene outlet from the reactor, PDEB=PEB/YX * (1-0.99)

= 47.09/0.99 (0.9) * (0.01)

n6 = 0.53 kmol/hour

The results of calculations are tabulated as in Table 2.3. It is shown from total

of mass balance, the calculation is considered balanced.

Table 2.3: Summary of Mass Balance.

SpeciesInlet

(kmol/hour)Outlet

(kmol/hour)Inlet

(kg/hour)Outlet

(kg/hour)

Benzene 158.55 110.99 12384.3405 8669.4289Ethylene 52.85 5.29 1482.4425 148.3845

Ethylbenzene 0 47.09 0 4999.5453Diethylbenzene 0 0.53 0 71.1366

Total 211.4 163.9 13866.783 13888.4953

2.4 Energy Balance

In this part, only energy balance in the packed bed reactor will be calculated

accordingly. Figure 2.2 shows input-output structure of temperature in the said reactor, where

temperature feed is at 298K, while the temperature outlet is 573K. The reactor operates at

573K and 5000 kPa.

Figure 2. 2: Input-output structure of temperature in reactor

The assumptions for energy balance calculation are as follows;

The process follow the law of conservation of energy where:

Energy out = Energy in + Generation – Consumption –Accumulation

Steady-state condition in all equipment.

Kinetic energy, potential energy and shaft work change for these streams will be

neglected and only enthalpy changes take place. Hence the energy balance equation

equal to Q = ∆H

Ideal properties for evaluating the energy balances of the process streams. This means

the pressure effect can be neglected.

No heat of mixing and pressure effect on ∆H.

Reference temperature for all the calculation is 1 atm and 25°C.

Figure 2.3 shows structure of enthalpy path of reaction from 298K to 573K, where ∆H

is enthalpy change of the reaction, ∆H°rxn is heat of reaction of benzene and ethylene to

ethylbenzene at 298K and ∆HP, 1 denotes enthalpy change of ethylbenzene from 298K to

573K.

Figure 2. 3: Enthalpy structure for energy balance

As both ethylene and benzene enter in gas phase at 298K (Smith, 1925), no heat of

vaporization is required. To aid the calculation, thermodynamic properties is tabulated as in

Table 2.4.

Table 2.4: Thermodynamic Properties of the Species Involved (Smith, 1925)

Species A B (103) C (106)C2H4 (Ethylene) 1.424 14.394 -4.392C6H6 (Benzene) -0.206 39.064 -13.301

C6H5C2H5 (Ethylbenzene) 1.124 55.380 -18.476

2.4.1 Heat of Reaction, ∆H°rxn at 298 K:

According to Smith (1925), the heat of reaction of ethylene, benzene, and

ethylbenzene are as follows;

ΔH˚f 298°C Ethylene (gas) : 52510 J/mol

ΔH˚f 298°C Benzene (gas) : 82930 J/mol

ΔH˚f 298°C Ethylbenzene (gas) : 29920 J/mol

∆ H ° rxn=∑ ∆ H °rxn PRODUCT−∆ H ° rxn REACTANT

From equation above,

∆H°rxn = 29920 – 82930 – 52510

∆H°rxn = -105520 J/mol

The heat of reaction is calculated by using formula;

Δ H ˚ R=R ∫773 K

298 K

( A+BT+C T 2+DT 3 ) dT T [¿ ] K

The heat of reaction of Benzene from 298 K to 573 K

Δ H ˚ R ,C6H6 = 3904.97 J/mol

The heat of reaction of Ethylene from 298 K to 573 K

Δ H ˚ R ,C2H4 = 1878.78 J/mol

The heat of reaction of Ethylbenzene from 298 K to 573 K

Δ H ˚ R ,C6H5C2H5 = 5945.88 J/mol

The total heat of reaction of benzene, ethylene, ethylbenzene from 298 K to 573 K

∆HP,1 = Δ H ˚ R ,C6H6 + Δ H ˚ R ,C2H4 + Δ H ˚ R ,C6H5C2H5

= 3904.97 +1878.78 + 5945.88

= 11729.63 J/mol

To find the total heat of reaction

Total, ΔH = ∆H°rxn + ∆HP,1

= -105520 +11729.63

= - 93, 790.37 J/mol

Since alkalynation of ethylbenzene is exothermic reaction, the heat of reaction

calculated have negative value indicated it is in exothermic reaction.

CHAPTER 3

REACTOR SIZING CONSIDERING MAIN REACTION

3.1 Reactor Sizing According Algorithm

The reactor is determined to packed bed reactor. Manually, calculation is done by

following the algorithm as studied.

Recall the reaction,

C6 H 6+C2 H 4→ C8 H 10

A+B →C

Mechanism,

Adsorption: A+S → A . SB+S → B . S

Surface area: A . S+B . S →C . S+SDesorption: C . S →C+S

Rate law,

Adsorption: −r A 1=k A' [P AC v−

C A. S

K A]

−r A 2=k B' [PB C v−

CB .S

KB]

Surface area: −r S=k S' [C A. SCB .S−

CC . SC v

K S]

Desorption: −r D=k D' [CA .S−

PC C v

K D] , assume

1K D

=KC

And it is assumed that the limiting step is surface reaction,

−r A1

k 'A

≈ 0

C A. S=PA C v K A ………… ..(1)

−r A2

k 'B

≈ 0

CB. S=PBC v KB ………… ..(2)

−r D

k ' D

≈ 0

CC .S=PC C v KC ………… ..(3)

−r S=k S' [C A. SCB .S−

CC . SC v

K S]………….(4 )

Site balance,

CT ¿C v+CA .S+CB .S+CC . S

¿C v+ PA C v K A+PB C v K B+PC C v KC

¿C v [1+PA K A +PB KB+PC KC ]C v ¿

CT

[1+P A K A+PB K B+PC K C ]…………… ..(5)

substitute (1),(2),(3)and (5) into (4)

−r S ¿k ' S[PA C v K A PBC v KB−PC C v KC C v

K S]

¿k ' S[PA PB K A K BC v2−

PC C v2

K S K D]

¿k ' S[PA PB K A K BC v2−

PC C v2 K A KB

K S K D K A KB]

−r S ¿k ' S K A KB C v2[P A PB−

PC

K eq], assuming K eq=KS K D K A KB

−r S¿

k 'S K A K B CT2 [PA PB−

PC

K eq]

1+PA K A+PB K B+PC KC

−r S¿

k PA PB

[1+P A K A+PB K B+PC K C ]2, assumingk=k ' S K A KB CT

2

Stoichiometry

Species Inlet Change Outlet Concentration

A Benzene F A0 −F A0 X F A=F A0(1−X )C A=C A0( 1−X

1+εX )(T 0

T ) y

B Ethylene F A0 θB −F A0 X FB=F A0(θ¿¿B+ X )¿CB=C A 0( θB−X

1+εX )(T 0

T ) y

C Ethylbenzene F A0 θC F A0 X FC=FA 0(θ¿¿C+X )¿CC=C A0( θC+X

1+εX )(T 0

T ) y

Rearranging PressurePA

RT=

P A0

R T 0( 1−X1+εX )(T 0

T ) y PA=PA0( 1−X1+εX ) y

PB

RT=

P A0

R T 0(θB−X

1+εX )(T 0

T ) y PB=PA0( θB−X

1+εX ) y

PC

RT=

P A0

R T 0(θC+ X

1+εX )(T 0

T ) y PC=PA 0( θC+X

1+εX ) y

Where

k 1[ kmol/m3 cat/h/atm2 ]=0. 69×106 exp (−6 . 344 X 10 4

RT )K A [atm -1 ]=1 .2328×10−17 exp(162 ,730

RT )K B [atm -1 ]=2 .0850×10−4 exp (35 ,368

RT )

K A [atm -1 ]=−1 .5202×10−2 exp (−3 . 933 X 10 4

RT )Design Equation

F A0dXdW

=−r 'A

dydW

=−α2 y

(1+εX )

Rate law

−r S=k PA PB

[1+PA K A+PB K B+PC KC ]2

Stoichiometry

PA=PAO (1−X )

1+εX

PB=P AO(5−X)

1+εX

PC=PAO X

1+εX

Combine

F A0dXdW

=k PA PB

[1+PA K A +PB KB+PC KC ]2

FAO = 158.55 kmol/hr

PAO = 5000 kPa

Temperature reactor = 573 K

3.2 Catalyst Determination

It is chosen that zeolite is the catalyst for this Ethylbenzene production. And its

properties is evaluated as below;

Dp = 0.0005 m = 1.6404 x 10-3 ft

Void fraction = 0.45

P=PAO

y AO

= 50000.16667

= 30 000 kPa = 297 atm

Bulk density of catalyst = ρc = 2200 kg/m3 = 62.99 kg/ft3

Ac = 0.0144 ft2 = 0.0013378 m2

Q = 1.2928 m3/s

u = Ac x Q = 1.2928 x 0.0013378 = 1.7295 x 10-3 kg/m2.s

gc = 32.174 lbm.ft/s2.lbf = 4.17 x 108 lbm.ft/h2.lbf

µ = 2.71 x 10-5 Pa.s = 0.06556 lbm/ft.h

ρ = 0.7 kg/m3 = 0.0437 lbm/ft3

G = ρu = 1.21067 kg/m2.s = 0.8927 lbm / ft2.h

Therefore,

β0=G (1−∅ )

ρ0 gc DP∅3 [ 150 (1−∅ ) μ

DP

+1.75 G ]

¿(0.81986 ) (1−0.45 )

(0.0437 ) (4.17 X 108 ) ( 1.6404 X 10−3 ) (0.453 ) [ (150 ) (1−0.45 ) (0.06556 )(1.6404 X 10−3 )

+1.75 (0.81986 )]

β0=0.54605lbf

ft2=2.5796 X 10−4 atm

ft

α=2 β0

ρc (1−∅ ) Ac P0

¿(2)(2.5796 X 10−4)

(0.0144 )(62.99)(1−0.45)(297)

α=3.482 X 10−6 kg−1

3.3 POLYMATH Result

In order to find the weight of catalyst, the simulation is ran by using Polymath

software as shown below,

POLYMATH Report No Title Ordinary Differential Equations 30-Dec-2014

Calculated values of DEQ variables

  Variable

Initial value

Minimal value

Maximal value

Final value

1 A 3.482E-06 3.482E-06 3.482E-06 3.482E-06

2 E -0.1666667 -0.1666667 -0.1666667 -0.1666667

3 Fao 158.55 158.55 158.55 158.55

4 k1 1.136199 1.136199 1.136199 1.136199

5 Ka 0.0084311 0.0084311 0.0084311 0.0084311

6 Kb 0.3494354 0.3494354 0.3494354 0.3494354

7 Kc -3.949E-06 -3.949E-06 -3.949E-06 -3.949E-06

8 Pa 5000. 0 5000. 0

9 Pao 5000. 5000. 5000. 5000.

10

Pb 2.5E+04 2.372E+04 2.5E+04 2.372E+04

11

Pc 0 0 5993.528 5928.934

12

R 8.314 8.314 8.314 8.314

13

r1 -1.842766 -1.842766 0 0

14

rT -1.842766 -1.842766 0 0

15

T 573. 573. 573. 573.

16

W 0 0 8100. 8100.

17

X 0 0 1. 1.

18

y 1. 0.9881557 1. 0.9881557

Differential equations 1 d(X)/d(W) = -rT/Fao

  design equation for packed bed reactor

2 d(y)/d(W) = - A * (1+(E*X))/(2*y)

Explicit equations 1 Fao = 158.55

2 Pao = 5000

3 E = -1/6

4 R = 8.314

5 T = 573

6 k1 = 0.69 *10^(6)* exp(-6.344*10^4/(R*T))

7 Ka = 1.2328 *10^(-17) * exp (162730/(R*T))

8 Kb = 2.085*10^(-4) * exp(35368/(R*T))

9 Kc = -1.5202 *10^(-2) * exp(-3.933*10^4/(R*T))

10 Pa = Pao * y*(1-X) /(1+E*X)

11 Pb = Pao *y* (5 - X)/(1+E*X)

12 Pc = Pao *y* (X)/(1+E*X)

13 r1 = -k1 * Pa * Pb / (1 + Ka * Pa + Kb * Pb + Kc * Pc)^2

14 A = 3.482*10^(-6)

  alpha

15 rT = r1

General Total number of equations 17

Number of differential equations 2

Number of explicit equations 15

Elapsed time 0.000 sec

Solution method RKF_45

Step size guess. h 0.000001

Truncation error tolerance. eps 0.000001

Figure 3. 1: Graph obtained from Polymath simulation

W X X calc X residual X residual ^20 0 0.767278907 0.767278907 0.588716922

22.95491 0.2396088 0.774224554 0.534615754 0.28581400440.55491 0.3891483 0.779549923 0.390401623 0.15241342749.35491 0.4539301 0.782212608 0.328282508 0.10776940558.15491 0.5126204 0.784875292 0.272254892 0.07412272666.95491 0.565648 0.787537977 0.221889977 0.04923516284.55491 0.656403 0.792863346 0.136460346 0.01862142693.35491 0.6949469 0.795526031 0.100579131 0.010116162102.1549 0.7294536 0.798188713 0.068735113 0.004724516110.9549 0.7602877 0.800851397 0.040563697 0.001645414128.5549 0.8122901 0.806176767 -0.006113333 3.73728E-05137.3549 0.8340773 0.808839451 -0.025237849 0.000636949146.1549 0.8534292 0.811502136 -0.041927064 0.001757879154.9549 0.8705981 0.814164821 -0.056433279 0.003184715172.5549 0.8992874 0.81949019 -0.07979721 0.006367595181.3549 0.9112068 0.822152875 -0.089053925 0.007930602190.1549 0.9217439 0.82481556 -0.09692834 0.009395103198.9549 0.9310528 0.827478244 -0.103574556 0.010727689216.5549 0.9465244 0.832803614 -0.113720786 0.012932417225.3549 0.9529215 0.835466298 -0.117455202 0.013795724234.1549 0.9585615 0.838128983 -0.120432517 0.014503991242.9549 0.9635323 0.840791668 -0.122740632 0.015065263260.5549 0.9717691 0.846117037 -0.125652063 0.015788441269.3549 0.9751658 0.848779722 -0.126386078 0.015973441278.1549 0.9781561 0.851442406 -0.126713694 0.01605636286.9549 0.9807882 0.854105091 -0.126683109 0.01604861304.5549 0.9851426 0.859430461 -0.125712139 0.015803542313.3549 0.9869357 0.862093145 -0.124842555 0.015585663

Table 3. 1: Result of simulation

From Table 3.1, at approximately 90% conversion the weight of catalyst required is

172.55 kg. Hence, analyzing the reactor sizing,

AC = 0.0144 ft2 = 0.0013378 m2

ρb=2200 (1−0.45 )=1210kg

m3

L= WAC ρb

¿ 172.55(0.0013378)(1210)

= 106.60 m

D= L6

= 17.76 m

It is determined that the length of the reactor is 106.6 m while its diameter is 17.76 m

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