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MANUFACTURE OF FORMALDEHYDE FROM METHANOL
A PROJECT REPORT Submitted by S. GAYATHRI (41501203005) G. MUTHAMILARASI (41501203014)
in partial fulfillment for the award of the degree of BACHELOR OF TECHNOLOGY in CHEMICAL ENGINEERING
S.R.M. ENGINEERING COLLEGE, KATTANKULATHUR-603 203, KANCHEEPURAM DISTRICT. ANNA UNIVERSITY : CHENNAI - 600 025 MAY 2005
Certified that this project report "MANUFACTURE OF FORMALDEHYDE FROM METHANOL" is the bonafide work of "S. GAYATHRI (41501203005) and G. MUTHAMILARASI (41501203014)" who carried out the project work under my supervision.
Prof. Dr. R. KARTHIKEYAN HEAD OF THE DEPARTMENT CHEMICAL ENGINEERING S.R.M.Engineering College Kattankulathur - 603 203 Kancheepuram District
Prof. Dr. R. KARTHIKEYAN SUPERVISOR PROFESSOR & HEAD CHEMICAL ENGINEERING S.R.M.Engineering College Kattankulathur - 603 203 Kancheepuram District
ACKNOWLEDGEMENT Our heart felt thanks to the Director, Dr.T.P.Ganesan, and our Principal, Prof. R.Venkatramani,M.Tech,F.I.E, for allowing us to carryout our project. We express our profound gratitude to Dr.R.Karthikeyan, Head of the
Department, Chemical engineering, who guided us in the right direction through the course of our project. We also thank our project co-ordinater Mrs.K.Kasturi,B.Tech, for her valuable advice and encouragement.
Our special thanks to the members of the DTP section and library for their cooperation
Formaldehyde, one of the important industrial chemicals, finds its applications in polymeric resins like phenol formaldehyde, adhesives, alkali resins for paints and coatings etcManufacture of formaldehyde (as formalin) is done by oxidation of methanol, mainly by metal oxide process involving Fe/Mo catalyst with 95-99mol% conversion of methanol. This project is aimed at designing plant producing 37 wt% formalin and checking for feasibility of production.
TABLE OF CONTENTS CHAPTERS TITLE ABSTRACT vii LIST OF TABLES viii LIST OF FIGURES LIST OF SYMBOLS 1 2 INTRODUCTION PROPERTIES 2.1 PHYSICAL PROPERTIES 2.2 THERMAL PROPERTIES 2.3 CHEMICAL PROPERTIES ANALYSIS AND SPECIFICATIONS COMMERCIAL USES OF FORMALIN LITERATURE REVIEW 5.1 SELECTION OF PROCESS PROCESS DESCRIPTION 6.1 FLOW SHEET MATERIAL BALANCE ENERGY BALANCE DESIGN PLANT LAYOUT MATERIALS OF CONSTRUCTION 11.1 METALS 11.2 NON-METALS INSTRUMENTATION AND CONTROL ix 1 3 3 3 4 7 8 10 11 12 14 15 19 23 29 39 39 40 41 PAGE NO iv
3 4 5
7 8 9 10 11
13 14 15 16
STORAGE AND TRANSPORTATION HEALTH AND SAFETY CONSIDERATIONS COST ESTIMATION CONCLUSION REFERENCES
46 47 49 56 57
LIST OF TABLESTable Number 1 2 3 4 5 6 7 Description Page No
Heat transfer data Storage temperatures Dose-response relationship Delivered cost of equipments Direct cost factor Indirect cost factor Auxillary cost factor
19 46 47 49 50 50 52
LIST OF FIGURES Page No FIGURE 6.1 FIGURE 7.1 FIGURE 7.2 FIGURE 8.1 FIGURE 8.2 FIGURE 8.3 FIGURE 8.4 FIGURE 8.5 FIGURE 8.6 FIGURE 10.1 FLOW SHEET REACTOR BALANCE ABSORBER BALANCE ENERGY BALANCE FOR METHANOL VAPORIZER ENERGY BALANCE FOR REACTOR ENERGY BALANCE FOR HEAT EXCHANGER 1 ENERGY BALANCE FOR HEAT EXCHANGER 2 ENERGY BALANCE FOR ABSORBER(BOTTOM) ENERGY BALANCE FOR ABSORBER (TOP) PLANT LAYOUT 14 17 18 19 20 21 21 21 22 38
LIST OF SYMBOLS A D,d L m Nu n P Pr Re V T U Area (m2) Diameter (m) Length (m) Mass (Kg) Nusselt number Number of tubes Pressure (atm) Prandtl number Reynolds number Volume(m3) Temperature(K) Overall heat transfer coefficient(W/ m2.oC) Z GREEK LETTERS T TL L Temperature difference (oC) Logarithmic mean temperature difference (oC) Viscosity of liquid Density (Kg/m3) Height (m)
1. INTRODUCTION Formaldehyde occurs in nature and it is formed from organic material by photochemical processes in the atmosphere. Formaldehyde is an important metabolic product in plants and animals (including humans), where it occurs in low but measurable concentrations. It has a pungent odour and is an irritant to the eye, nose and throat even at low concentrations. However, Formaldehyde does not cause any chronic damage to human health. Formaldehyde is also formed when organic material is incompletely combusted. Formaldehyde is an important industrial chemical and is employed in the manufacture of many industrial products and consumer articles. Formaldehyde was first synthesized in 1859, when BUTLEROV hydrolyzed methylene acetate and noted the characteristic odour of the resulting solution. In 1867,HOFMANN conclusively identified formaldehyde, which he prepared by passing methanol vapour and air over a heated platinum spiral. This method, but with other catalyst, still constitutes the principal method of manufacture. Industrial production of formaldehyde became possible in 1882,when TOLLENS discovered a method of regulating the methanol vapour: air ratio and affecting the yield of the reaction. In 1886 LOEW replaced the platinum spiral catalyst by more efficient copper gauze. A German firm, Hugo Blank, patented the first use of a silver catalyst in 1910.In 1905,Badische Anilin and Soda-Fabrik started to manufacture formaldehyde by a continous process employing a crystalline catalyst. Formaldehyde output was 30 kg/day in the form of an aqueous 30 wt% solution. The methanol required for the production of formaldehyde was initially obtained from the timber industry by carbonizing wood. The development of high-pressure synthesis of methanol by Badische Anilin and Soda-Fabrik in 1925 allowed the production of formaldehyde on a true industrial scale
2. PROPERTIES 2.1 PHYSICAL PROPERTIES Formaldehyde is a colorless gas at ambient temperature that has a pungent, suffocating odor. At ordinary temperatures formaldehyde gas is readily soluble in water, alcohols and other polar solvents. It has following physical properties: Boiling point at 101.3 kPa = -19.2oC Melting point = -118oC Density at 80oC = 0.9151g/cm3 At 20oC = 0 .8153 g/cm3 Vapor density relative to air = 1.04 Critical temperature = 137.2 141.2 (oC) Critical pressure = 6.784 6.637 Mpa Cubic expansion coefficient = 2.83 x 103 K-1 2.2 THERMAL PROPERTIES Heat of formation at 25oC = -115.9 + 6.3 kJ/mol Heat of combustion at 25oC = 561.5 kJ/mol Heat of vapourisation at 19.2oC = 23.32 kJ/mol Specific heat capacity at 25oC = 35.425 J/mol K Heat of solution at 23oC In water = 62 kJ/mol In methanol= 62.8 kJ/mol In 1-propanal = 59.5 kJ/mol In 1-butanol = 62.4 kJ/mol Entropy at 25oC= 218.8 + 0.4 kJ/mol K 2.3 CHEMICAL PROPERTIES Formaldehyde is one of the most reactive organic compounds known. The various chemical properties are as follows: Decomposition At 150oC formaldehyde undergoes heterogeneous decomposition to form methanol and CO2 mainly. Above 350oC it tends to decompose in to CO and H2.
Polymerization Gaseous formaldehyde polymerizes slowly at temperatures below 100oC, polymerization accelerated by traces of polar impurities such as acids, alkalis or water. In water solution formaldehyde hydrates to methylene glycol H H2C=O + H2O HO C H Which in turn polymerizes to polymethylene glycols, HO (CH2O)nH, also called polyoxy methylenes. Reduction and Oxidation Formaldehyde is readily reduced to methanol with hydrogen over many metal and metal oxide catalysts. It is oxidized to formic acid or CO2 and H2O. In the presence of strong alkalis or when heated in the presence of acids formaldehyde undergoes cannizzaro reaction with formation of methanol and formic acid. In presence of aluminum or magnesium methylate, paraformaldehyde reacts to form methyl formate (Tishchenko reaction) 2HCHO Addition reactions The formation of sparingly water-soluble formaldehyde bisulphite is an important addition reaction. Hydrocyanic acid reacts with formaldehyde to give glyconitrile. HCHO + HCN HOCH2 - C N HCOOCH3 OH
Formaldehyde undergoes acid catalyzed Prins reaction in which it forms -Hydroxymethylated adducts with olefins. Acetylene undergoes a Reppe addition reaction with formaldehyde to form 2- butyne-1,4- diol.
2 HCHO + HC CH
Strong alkalis or calcium hydroxide convert formaldehyde to a mixture of sugars in particular hexoses, by a multiple aldol condensation, which probably involves a glycolaldehyde intermediate. Acetaldehyde, for example reacts with formaldehyde to give pentaerythritol, C (CH2OH)4 Condensation reactions Important condensation reactions are the reaction of formaldehyde with amino groups to give schiffs bases, as well as the Mannich reaction. CH3COCH3 + (CH3)2NH.HCl
CH3COCH2CH2N(CH3) 2.HCl + H2O Formaldehyde reacts with ammonia to give hexamethylene teteramine and with ammonium chloride to give monomethylamine, dimethylamine, or trimethylamine and formic acid, depending upon reaction conditions. Aromatic compounds such as benzene, aniline, and toluidine combine with formaldehyde to produce the corresponding diphenyl methanes. In the presence of hydrochloric acid and formaldehyde, benzene is chloromethylated to form benzyl chloride. Formaldehyde reacts with hydroxylamine, hydrazines, or semicardazide to produce formaldehyde oxime, the corresponding hydrazones, and semicarbazone, respectively. Resin formation Formaldehyde condenses with urea, melamine, urethanes, cyanamide, aromatic sulfonamides and amines, and phenols to give wide range of resins.
3. ANALYSIS AND SPECIFICATIONS Qualitative Methods: Qualitative detection of formaldehyde is primarily by colorimetric methods. Schiffs fuchsin-bisulfite reagent is the general reagent used for detecting aldehydes. In the presence of strong acids, it reacts with formaldehyde to form a specific bluish violet dye. Quantitative Methods: Physica