Systematic Generation of Reactions Pathways for Manufacturing Bulk Industrial Chemicals from Biomass

Abstract

The objective of this work was to develop a systematic strategy for generating efficient, alternate reaction paths that could be used to manufacture the top 100 industrial chemicals, currently produced from crude oil, using renewable feedstocks. Manufacturing these chemicals from oil, coal, or natural gas results in increasing carbon dioxide levels in the atmosphere, responsible for global climate change. The methodology employed here uses the existing knowledge on the conversion of carbon-neutral feedstocks, such as biomass, wood, etc., to suitable precursor raw materials. Known industrial reaction paths, currently used for manufacturing the top 100 industrial organic chemicals, are then combined with the known conversion of carbon-neutral feedstocks to systematically develop and evaluate alternate carbon-efficient reaction paths. The fractional carbon economy was determined from a comprehensive listing of industrial reactions paths, which also gives the yields and efficiencies of these industrial reaction paths, currently being practiced in the chemical industry. Reaction pathways with maximum carbon economy for manufacturing the top 100 industrial chemicals from carbon-neutral feedstocks have been presented in this chapter.

1. Introduction

Sustainable production of industrial chemicals requires the use of biomass as a raw material, which can be converted into intermediate chemicals, currently being used as raw materials derived from non-renewable feedstocks, such as coal, crude oil, natural gas, etc. This allows the chemical industry to preserve its current petrochemical plants, except changing its source of feedstock from nonrenewable sources to renewable materials, such as biomass. The challenges posed by shifting to renewable feedstocks involve new chemistries which convert a variety of biomass materials into the known feedstocks, and in some cases starting with completely different raw materials. In addition, biomass conversions by fermentation involve slow reactions, conducted in the liquid phase, with low conversions, resulting in dilute aqueous solutions.

Traditionally, the chemical industry has relied on gas phase, catalytic, high temperature, and often high-pressure reactions, which require short residence times in smaller reactors and produce a high concentration of product(s). In comparison, biomass conversions using fermentation are biological, liquid-phase reactions, conducted at near ambient temperature and usually atmospheric pressure. The reaction rates in fermentation chemistry are orders of magnitude lower than in gas-phase chemical conversions.

Notwithstanding these challenges, in this chapter, known reactions for converting a variety of biomass sources into known chemical feedstocks have been detailed. Conversion and yield information from the publications of these chemical reactions was used to generate and rank these reactions based on their carbon economy. Carbon economy is the ratio of the mass of carbon atoms in the feedstock produced to the mass of carbon atoms present in the biomass source. By maximizing the carbon economy, the mass of carbon atoms present in the waste product(s) is minimized.

In addition, chemical reaction pathways, currently used to manufacture the top 100 industrial chemicals from nonrenewable feedstocks, were derived from known sources [1, 2, 3, 4], and each reaction pathway was also evaluated by its carbon economy. A computer program was developed to link the biomass conversion reactions with the industrial chemical pathways, with the objective of maximizing the overall carbon economy starting with the biomass material and ending with the industrial chemical. This provided multiple reaction pathways, in order of decreasing the overall carbon economy, to convert a biomass feedstock to each of the top 100 industrial chemicals.

2. Biomass conversion reaction pathways

In our analysis, seventeen different biomass materials were considered and information on the conversion of these biomass materials to known feedstock chemicals was derived from publications cited in this section.

Seventeen biomass sources, considered in this paper, are as follows:

• Beech wood

• Pine sawdust

• Municipal solid waste (pilot plant)

• Sewage sludge

• Sunflower residue

• Rape residue

• Switchgrass

• Sunflower shells

• Rice husk

• Pine chip

• Tropical lauan

• Paddy straw

• Corn cob

• Yellow poplar sawdust

• Alaskan spruce

• Wheat straw

• Rice hulls

The biomass conversion processes employed to convert these biomass sources to feedstock chemicals include pyrolysis, which is heating the biomass material, either in the presence of a catalyst, such as alumina, or noncatalytically. The flash pyrolysis process is conducted in an oxygen-free, inert gas atmosphere in the temperature range of 600–1000°C and 1 atmosphere pressure. Products of pyrolysis consist of gases, such as carbon monoxide, carbon dioxide, methane, etc., and liquids, such as heavier hydrocarbon oils and ammonia.

Another biomass conversion process used is hydrothermal liquefaction, where the biomass material, once shredded into small pieces, is heated in water under hydrothermal pressures and temperatures ranging from 500 to 700°C. This converts the biomass material into a liquid oil product, which is then processed as crude oil, using cracking and distillation.

Gasification of biomass under controlled oxidative conditions produces synthesis gas, which can be converted to chemicals using the well-known Fisher-Tropsch chemistry.

Hydrolysis, using acids, followed by fermentation converts biomass into chemicals, such as ethanol, acetic acid, etc. These chemicals become the feedstocks for a variety of industrial chemicals.

Table 1 lists the chemical composition of the various biomass sources and their carbon economy [5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20].

Biomass source	% Carbon	% Hydrogen	% Oxygen	% Carbon economy	Reference
Beechwood	48.4	6.2	45.0	0.48	[5]
Pine sawdust	48.3	6.5	45.2	0.48	[6]
Municipal solid waste	52.3	6.5	38.3	0.52	[7]
Sewage sludge	49.5	7.3	35.6	0.50	[8]
Sunflower residue	43.6	5.8	49.3	0.44	[9]
Rape residue	44.7	5.8	48.1	0.45	[9]
Switch grass	46.8	5.1	42.1	0.47	[10]
Sunflower shells	41.5	6.1	39.8	0.42	[11]
Rice husk	38.3	4.4	35.4	0.38	[12, 13]
Pine chips	51.7	6.1	41.8	0.52	[14]
Tropical luan	51.1	6.3	42.4	0.51	[14]
Paddy straw	35.6	5.3	43.1	0.36	[15]
corn cob	46.6	5.9	45.5	0.47	[16]
Yellow poplar sawdust	48.5	5.9	43.7	0.48	[17]
Alaskan spruce	50.1	6.2	42.9	0.50	[12]
Wheat straw	43.2	5.0	39.4	0.43	[18]
Wood	48.4	6.2	45.0	0.48	[19]
Rice hulls	66.0	7.2	25.4	0.66	[20]

Table 1.

Biomass sources, composition and carbon economy.

3. Reactions for manufacturing industrial chemicals

Production of industrial chemicals utilizes a variety of reactions to convert the raw materials to the desired products. The following is a list of the reactions involved in the manufacture of the top 100 industrial chemicals and their chemical classification.

• Methane → acetylene: pyrolysis

• Acetylene → ethylene: hydration

• Ethanol → ethylene: dehydration

• Propane → acetylene: pyrolysis

• Isobutane → isobutylene: dehydrogenation

• N-butane → N-butylene: dehydrogenation

• Acetylene → butadiene: reaction of acetylene and formaldehyde

• Ethanol → butadiene: dehydration/dehydrogenation

• Ethylene → ethanol: hydration

• Benzene → cyclohexane: hydrogenation

• Benzene → ethyl benzene: reaction of benzene and ethylene

• Ethylene → acetaldehyde: oxidation

• Carbon monoxide → methanol: hydrogenation

• Methanol → acetic acid: carbonylation

• Acetic acid → acetic anhydride: reaction of acetic acid and ketone

• Acetic acid → acetone: decarboxylation

• Acetaldehyde → acrolein: reaction of acetaldehyde and formaldehyde

• Acetic acid → acrylic acid: reaction of acetic acid and formaldehyde

• Butadiene → adiponitrile: chlorination of butadiene with sodium cyanide

• Propylene → allyl chloride: chlorination of propylene

• Allyl chloride → allyl alcohol: hydrolysis

• Acetylene → acetaldehyde: hydration

• Acetaldehyde → crotonaldehyde: dimerization

• Crotonaldehyde → N-butanol: hydrogenation

• Ethanol → acetaldehyde: oxidation

• Crotonaldehyde → N-butyraldehyde: hydrogenation

• N-butyraldehyde → N-butanol: hydrogenation

• N-butylene → S-butanol: sulfonation

• Benzene → chlorobenzene: oxychlorination

• Benzene → cumene: reaction of benzene and propylene

• Cyclohexane → cyclohexanol: oxidation-boron assisted

• Cyclohexanol → cyclohexanone: dehydrogenation

• Methanol → formaldehyde: oxidation

• Formaldehyde → ethylene glycol: carbonylation

• Ethylene glycol → diethylene glycol: reaction of ethylene glycol and ethylene oxide

• Toluene → dinitrotoluene: nitration

• Acrolein → epichlorohydrin: chlorination

• Ethylene → ethylene dichloride: chlorination

• Ethylene → ethylene oxide: chlorohydration

• Propylene → isopropanol: hydration

• Acetic acid → ketene: pyrolysis

• Methane → methyl chloride: chlorination

• Methanol → methyl chloride: hydrochlorination

• Benzene → nitrobenzene: nitration

• Acetaldehyde → peracetic acid: oxidation

• Benzene → phenol: sulfonation

• Carbon monoxide → phosgene: reaction of carbon monoxide and chlorine

• Naphthalene → phthalic anhydride: oxidation

• Propylene → propylene dichloride: chlorination

• Propylene → propylene oxide: chlorohydration

• Toluene → terephthalic acid: reaction of toluene and carbon monoxide

• Dinitrotoluene → toluene diamine: hydrogenation

• Acetylene → trichloroethylene: chlorination

• Ethylene dichloride → trichloroethylene: chlorination

• Acetylene → vinyl chloride: hydrochlorination

• Ethylene dichloride → vinyl chloride: dehydrochlorination

• Acetylene → acrylonitrile: cyanation

• Acetaldehyde → acrylonitrile: cyanation/dehydration

• Benzene → aniline: reaction of benzene and ammonia

• Toluene → benzoic acid: oxidation

• Phenol → bisphenol-A: reaction of phenol and acetone

• Cyclohexane → caprolactam: nitration

• Methane → chloroform: chlorination

• Methyl chloride → chloroform: chlorination

• Acetylene → chloroprene: dimerization

• Butadiene → chloroprene: chlorination

• Phenol → cresylic acid: methylation

• Methane → carbon tetrachloride: chlorination

• Carbon tetrachloride → dichlorofluoromethane: reaction with hydrogen fluoride

• Methyl chloride → carbon tetrachloride: chlorination

• Terephthalic acid → dimethyl terephthalate: esterification

• Acetic acid → ethyl acetate: esterification

• Acrylic acid → ethyl acrylate: esterification

• Ethylene → ethyl chloride: hydrochlorination

• Ethylene → ethyl dibromide: bromination

• N-butyraldehyde → 2-ethylhexanol: dimerization

• Epichlorohydrin → glycerin: hydrolysis

• Adiponitrile → hexamethylenediamine: hydrogenation

• Acetone → isoprene: reaction of acetylene and acetone

• Benzene → maleic anhydride: oxidation

• Ethylene dichloride → methyl chloroform: chlorination

• Methane → methylene dichloride: chlorination

• Methyl chloride → methyl dichloride: chlorination

• N-butylene → methyl ethyl ketone: oxidation

• Acetone → methyl isobutyl ketone: dimerization

• Acetone → methyl methacrylate: cyanation

• Carbon tetrachloride → perchloroethylene: pyrolysis

• Propylene oxide → propylene glycol: hydration

• Butadiene → styrene: cyclohydrogenation

• Toluene diamine → toluene diisocyanate: phosgenation

• Carbon tetrachloride → trichlorofluoromethane: reaction of carbon tetrachloride and hydrogen fluoride

• Ethylene oxide → ethylene glycol: hydration (in book)

• Diethylene glycol → triethylene glycol: reaction of diethylene glycol and ethylene oxide

• Carbon monoxide → urea: reaction of ammonia and carbon monoxide

• Acetic acid → vinyl acetate: reaction of acetylene and acetic acid

• Carbon monoxide → formic acid: hydrolysis

• Cyclohexanol → adipic acid: oxidation

• Methane → hydrogen cyanide: ammoxidation

• Propane → hydrogen cyanide: reaction of propane and ammonia

• Carbon monoxide → isobutanol: reaction of carbon monoxide and hydrogen

Table 2 lists the chemical reactions, yield, and the calculated atom economy, used in the analysis, based on the reported reaction yields [4]. The following equation was used to calculate the carbon economy from the reported data and a balanced reaction pathway:

Industrial reaction	Yield (product/reactant)	Atom economy
Methane → acetylene	0.4545	0.5
Acetylene → ethylene	0.9174	1.0
Ethanol → ethylene	0.5848	1.0
Propane → acetylene	0.3448	0.50
Isobutane → isobutylene	0.6667	1.0
n-Butane → N-butylene	0.6667	1.0
Acetylene → butadiene	1.4925	1.0
Ethanol → butadiene	0.3333	1.0
Ethylene → ethanol	1.5152	1.0
Benzene → cyclohexane	1.0753	1.0
Benzene → ethyl benzene	1.3158	1.0
Ethylene → acetaldehyde	1.4925	1.0
Carbon monoxide → methanol	1.0	1.0
Methanol → acetic acid	1.8519	1.0
Acetic acid → acetic anhydride	1.6129	1.0
Acetic acid → acetone	0.4587	0.75
Acetaldehyde → acrolein	0.9524	1.0
Acetic acid → acrylic acid	1.20	1.0
Butadiene → adiponitrile	1.2195	1.0
Propylene → allyl chloride	1.4286	1.0
Allyl chloride → allyl alcohol	0.6667	1.0
Acetylene → acetaldehyde	1.6129	1.0
Acetaldehyde → crotonaldehyde	0.7407	1.0
Crotonaldehyde → n-butanol	1.0	1.0
Ethanol → acetaldehyde	0.8696	1.0
Crotonaldehyde → n-butyraldehyde	1.0	1.0
n-Butyraldehyde → n-butanol	0.9709	1.0
n-Butylene → butanol	1.1111	1.0
Benzene → chlorobenzene	1.2195	1.0
Benzene → cumene	1.2658	1.0
Cyclohexane → cyclohexanol	0.9709	1.0
Cyclohexanol → cyclohexanone	0.9524	1.0
Methanol → formaldehyde	0.8696	1.0
Formaldehyde → ethylene glycol	1.5385	1.0
Ethylene glycol → diethylene glycol	1.4286	1.0
Toluene → dinitro toluene	1.8519	1.0
Acrolein → epichlorohydrin	1.2847	1.0
Ethylene → ethylene dichloride	3.3333	1.0
Ethylene → ethylene oxide	1.25	1.0
Propylene → isopropanol	1.3889	1.0
Acetic acid → ketene	0.6289	1.0
Methane → methyl chloride	2.439	1.0
Methanol → methyl chloride	1.4286	1.0
Benzene → nitro benzene	1.5385	1.0
Acetaldehyde → peracetic acid	1.5625	0.5
Benzene → phenol	0.9009	1.0
Carbon monoxide → phosgene	0.9009	1.0
Naphthalene → phthalic anhydride	0.9524	0.8
Propylene → propylene dichloride	2.439	1.0
Propylene → propylene oxide	1.0638	1.0
Toluene → terephthalic acid	1.8043	1.0
Dinitro toluene → toluene diamine	0.6369	1.0
Acetylene → trichloroethylene	4.7619	1.0
Ethylene dichloride → trichloroethylene	1.2658	1.0
Acetylene → vinyl chloride	2.2727	1.0
Ethylene dichloride → vinyl chloride	0.5988	1.0
Acetylene → acrylonitrile	1.6667	1.0
Acetaldehyde → acrylonitrile	1.2045	1.0
Benzene → aniline	1.1923	1.0
Toluene → benzoic acid	1.1905	1.0
Phenol → bisphenol a	1.1364	1.0
Cyclohexane → caprolactam	0.7692	1.0
Methane → chloroform	7.1429	1.0
Methyl chloride → chloroform	2.2727	1.0
Acetylene → chloroprene	1.3333	1.0
Butadiene → chloroprene	1.3333	1.0
Butadiene → chloroprene	1.25	1.0
Phenol → cresylic acid	1.1494	0.5
Methane → carbon tetrachloride	9.0909	1.0
Carbon tetrachloride → dichlorofluoromethane	9.0909	1.0
Methyl chloride → carbon tetrachloride	2.7778	1.0
Terephthalic acid → dimethyl terephthalate	1.1494	1.0
Acetic acid → ethyl acetate	1.4493	1.0
Acrylic acid → ethyl acetate	1.2987	1.0
Ethylene → ethyl chloride	2.000	1.0
Ethylene → ethyl dibromide	6.2500	1.0
N-butyraldehyde → 2-ethyl hexanol	0.8130	1.0
Epichlorohydrin → glycerine	0.9524	1.0
Adiponitrile → hexamethylenediamine	1.0753	1.0
Acetone → isoprene	1.0526	1.0
Benzene → maleic anhydride	0.7692	0.66
Ethylene dichloride → methyl chloroform	1.2195	1.0
Methane → methylene dichloride	5.0000	1.0
Methyl chloride → methyl dichloride	1.6129	1.0
n-Butylene → methyl ethyl ketone	1.1111	1.0
Acetone → methyl isobutyl ketone	0.8000	1.0
Acetone → methyl methacrylate	1.3889	1.0
Carbon tetrachloride	0.5000	1.0
Propylene oxide → propylene glycol	1.1765	1.0
Butadiene → styrene	0.9696	1.0
Toluene diamine → toluene diisocynate	1.2048	1.0
Carbon tetrachloride → trichlorofluoromethane	0.7143	1.0
Ethylene oxide → ethylene glycol	1.1364	1.0
Diethylene glycol → triethylene glycol	2.8571	.10
Carbon monoxide → urea	1.3158	1.0
Acetic acid → vinyl acetate	1.3889	1.0
Carbon monoxide → formic acid	1.6428	1.0
Cyclohexanol → adipic acid	1.3699	1.0
Methane → hydrogen cyanide	1.2195
Propane → hydrogen cyanide	1.5625	1.0
Carbon monoxide → isobutanol	0.1499	0.8

Table 2.

Industrial chemical reactions, commercial yield and atom economy.

$$\begin{array}{c}\%\text{Carbon economy}=\left[\left(\text{Unit weight of product}\right)/\text{Unit weight of}\mathrm{raw}\text{material}\left(s\right)\right]\\ \times \left[\text{Molecular Weight of}\mathrm{raw}\text{material}\left(s\right)/\text{Molecular Weight of product}\right]\\ \times \left[\text{Moles of carbon in product}/\text{Moles of carbon in}\mathrm{raw}\text{materials}\right]\times 100.\end{array}$$E1

4. Reaction pathways from biomass to industrial chemicals

The reaction pathways for the top industrial chemicals, as listed in the previous section, were combined with the biomass conversion reactions to maximize the overall carbon economy. This yielded biomass conversion reaction pathways to the major industrial chemicals, and these conversion paths with the maximum carbon economy are listed in Table 3.

Industrial chemical	Reaction path with the highest carbon economy	Overall carbon economy
Butadiene	Beech wood → methane → acetylene → butadiene	0.4173
Di ethylene glycol	Pine saw dust → carbon monoxide → methanol → formaldehyde → ethylene glycol → di ethylene glycol	0.5940
Carbon monoxide	Pine saw dust → carbon monoxide	0.5940
Carbon dioxide	Beech wood → carbon dioxide	0.2923
Methane	Beech wood → methane	0.8346
Ethylene	Beech wood → methane → acetylene → ethylene	0.4173
Ethane	Alaskan spruce → ethane	0.0713
Acetylene	Beech wood → methane → acetylene	0.4173
Propylene	Beech wood → propylene	0.0236
Propane	Tropical luan → propane	0.1700
Isobutane	Sunflower residue → isobutane	0.0100
n-Butane	Sunflower residue → n-butane	0.0400
n-Butylene	Sunflower residue → methylene dichloride → n-butylene
n-Pentane	Cannot be produced from biomass
Iso-Pentane	Rape residue → iso-pentane	0.0300
Ethanol	Beech wood → methanol → acetylene → ethylene → ethanol	0.4173
Cyclohexane	Sewage sludge → benzene → cyclohexane	0.0852
Benzene	Sewage sludge → benzene	0.0852
Ethyl benzene	Sewage sludge → benzene → ethyl benzene	0.0852
Naphthalene	Alaskan spruce → naphthalene	0.0203
Toluene	Rice husk → toluene	0.0388
0-Xylene, m-Xylene	Cannot be produced from biomass
p-Xylene	Alaskan spruce → p-xylene	0.0096
Acetaldehyde	Beech wood → methane → acetylene → ethylene → acetaldehyde	0.4173
Acetic acid	Pine saw dust → carbon monoxide → methanol → acetic acid	0.5940
Acetic anhydride	Pine saw dust → carbon monoxide → methanol → acetic acid → acetic anhydride	0.5940
Acetone	Pine saw dust → carbon monoxide → methanol → acetic acid → acetone	0.4455
Acrolein	Beech wood → methane → acetylene → ethylene → acetaldehyde → acrolein	0.4173
Acrylic acid	Pine saw dust → carbon monoxide → methanol → acetic acid → acrylic acid	0.5940
Adiponitrile	Beech wood → methane → acetylene → butadiene → adiponitrile	0.4173
Allyl alcohol	Beech wood → propylene → allyl chloride → allyl alcohol	0.0236
Allyl chloride	beech wood ⇒ propylene → allyl chloride	0.0236
n-Butanol	beech wood → methane → acetylene → acetaldehyde → crotonaldehyde → n-butanol	0.3091
Iso-Butanol	sunflower residue → methylene dichloride → methyl iso butyl ketone → iso-butanol	0.0004
n-Butyraldehyde	Beech wood → methane → acetylene → acetaldehyde → crotonaldehyde → n-butyraldehyde	0.3091
Chlorobenzene	Sewage sludge → benzene → chlorobenzene	0.0852
Crotonaldehyde	Beech wood → methane → acetylene → ethylene → acetaldehyde → crotonaldehyde	0.3091
Cumene	Sewage sludge → benzene → cumene	0.0852
Cyclohexanol	Sewage sludge → benzene → cyclohexane → cyclohexanol	0.0852
Cyclohexanone	Sewage sludge → benzene → cyclohexane → cyclohexanol → cyclohexanone	0.0852
Dinitro toluene	Rice husk → toluene → dinitro toluene	0.0388
Epichlorohydrin	Beech wood → methane → acetylene → acetaldehyde → acrolein → epichlorohydrin	0.4173
Ethylene dichloride	Beech wood → methane → acetylene → ethylene → ethylene dichloride	0.4173
Ethylene oxide	Beech wood → methane → acetylene → ethylene → ethylene oxide	0.4173
Ethylene glycol	Pine saw dust → carbon monoxide → methanol → formaldehyde → ethylene glycol	0.5940
Iso-Butyraldehyde	Cannot be manufactured from biomass
Isopropanol	Beech wood → isoprene → isopropanol	0.0236
Ketene	One saw dust → ethyl acrylate → methanol → acetic acid → ketene	0.5940
Methanol	Pine saw dust → carbon monoxide → methanol	0.5940
Methyl chloride	Beech wood → methane → methyl chloride	0.8346
Nitro benzene	Sewage sludge → benzene → nitrobenzene	0.0852
Peracetic acid	Beech wood → methane → acetylene → acetaldehyde → peracetic acid	0.2087
Phenol	Sewage sludge → benzene → phenol	0.0852
Phosgene	Pine saw dust → ethyl acrylate → phosgene	0.5940
Acrylonitrile	Beech wood → ethylene dibromide → hexamethylene diamine → acrylonitrile	0.4173
Aniline	Sewage sludge → benzene → aniline	0.0852
Benzoic acid	Rice husk → toluene → benzoic acid	0.0388
Bisphenol A	Sewage sludge → benzene → phenol → bisphenol A	0.0852
Caprolactam	Sewage sludge → benzene → cyclohexane → caprolactam	0.0852
Chloroform	Beech wood → methane → chloroform	0.8346
Chloroprene	Beech wood → methane → acetylene → chloroprene	0.4173
Cresylic acid	Sewage sludge → benzene → phenol → cresylic acid	0.0426
Dichloro difluoro methane	Beech wood → methane → carbon tetrachloride → dichloro difluoro methane	0.8346
Dimethyl terephtalate	Rice husk → toluene → terepthalic acid dimethyl terephtalate	0.0388
Ethyl acetate	Pine saw dust → carbon monoxide → methanol → acetic acid → ethyl acetate	0.5940
Ethyl acrylate	Pine saw dust → carbon monoxide → methanol → acetic acid → acrylic acid → ethyl acrylate	0.5940
Ethyl chloride	Beech wood → methane → acetylene → ethylene → ethyl chloride	0.4173
Ethylene dibromide	Beech wood → methane → acetylene → ethylene → ethylene dibromide	0.4173
2-Ethyl hexanol	Paddy straw → ethanol → acetaldehyde → crotonaldehyde → n-butyraldehyde → 2-ethyl hexanol	0.2934
Glycerine	Paddy straw → ethanol → acetaldehyde → cumene → epichlorohydrin → glycerine	0.3961
Hexamethylene diamine	Beech wood → methane → acetylene → methyl methacrylate → adiponitrile → hexamethylene diamine	0.4173
Isoprene	Pine saw dust → carbon monoxide → methanol → acetic acid → acetone → isoprene	0.4455
Maleic anhydride	Sewage sludge → benzene → maleic anhydride	0.0852
Methyl chloroform	Beech wood → methane → acetylene → ethylene → ethylene dichloride → methyl chloroform	0.4173
Methylene dichloride	Beech wood → methane → methylene dichloride	0.8346
Methyl ethyl ketone	Sunflower residue → methylene dichloride → methyl iso butyl ketone → methyl ethyl ketone	0.0400
Methyl iso butyl ketone	Pine saw dust → carbon monoxide → methanol → acetic acid → acetone → methyl iso butyl ketone	0.4455
Methyl methacrylate	Pine saw dust → carbon monoxide → methanol → acetic acid → acetone → methyl methacrylate	0.4455
Perchloroethylene	Beech wood → propylene → carbon tetrachloride → perchloroethylene	0.8346
Propylene glycol	Beech wood → propylene → propylene oxide → propylene glycol	0.0236
Styrene	Beech wood → methane → acetylene → methyl methacrylate → styrene	0.4173
Toluene di isocyanate	Rice husk → toluene → dinitro toluene → toluene diamine → toluene di iso cyanate	0.0388
Trichloro fluoro methane	Beech wood → methane → carbon tetrachloride → trichloro fluoro methane	0.8346
Triethylene glycol	Beech wood → ethylene → ethylene oxide → ethylene glycol → diethylene glycol → triethylene glycol	0.0843
Urea	Pine saw dust → carbon monoxide → urea	0.5940
Vinyl acetate	Pine saw dust → carbon monoxide → methanol → acetic acid → vinyl acetate	0.5940
Hexane	Rape residue → hexane	0.0800
Formic acid	Pine saw dust → carbon monoxide → formic acid	0.5940
Adipic acid	Sewage sludge → benzene → cyclohexane → cyclo hexanol → adipic acid	0.0852
Carbon tetrachloride	Beech wood → methane → carbon tetrachloride	0.8346
Hydrogen cyanide	Beech wood → hydrogen cyanide	0.8346
Isobutanol	Pine saw dust → carbon monoxide → iso-butanol	0.4752

Table 3.

Chemical pathways for converting biomass to industrial chemicals with the overall carbon economy.

Although several biomass sources were used in the analysis, only beechwood, pine sawdust, sunflower residue, rape residue, sewage sludge, alaskan spruce, tropical luan, and rice husk were selected to maximize the overall carbon economy, with beechwood and pine sawdust being mostly used to generate the chemical intermediate. Sewage sludge was used to generate benzene as an intermediate chemical, which could then be converted to other aromatic compounds. The carbon economy for sewage sludge conversion to aromatics was less than 10%, which may render these chemical paths uneconomical.

The following examples from Table 3 illustrate the biomass conversion reactions which had the highest atom economy for two industrial chemicals.

Butadiene can be produced from biomass using the following steps:

1. Gasification of beech wood: conducted at 700°C and atmospheric pressure produces methane with an atom economy of 83.5% [7].

2. Conversion of methane to acetylene gas: using the arc process [3], methane is converted to acetylene gas with an atom economy of 50%; byproducts produced are ethylene and hydrogen gases.

3. Reaction of acetylene with formaldehyde [3]: product is butadiene and steam.

Figure 1 shows a schematic of the reaction pathway to convert beech wood to butadiene.

Figure 1.

Reaction path for manufacturing butadiene from beech wood.

Another example of a reaction pathway is the conversion of pine sawdust to diethylene glycol, and this reaction pathway with their respective atom economies is shown in Figure 2. This pathway has the highest carbon economy for manufacturing diethylene glycol from a biomass source.

Figure 2.

Reaction path for manufacturing Di ethylene glycol from pine sawdust.

5. Conclusions

Sustainable industrial chemistry requires “optimum” reaction pathways, as defined by the highest carbon economy, starting with various biomass materials. Biomass is a sustainable feedstock, while currently used starting materials, such as crude oil, coal, and natural gas, are unsustainable. Furthermore, when industrial chemicals are made from unsustainable feedstocks, they eventually add additional carbon to the environment, typically in the form of carbon dioxide, an earth warming gas. Manufacturing industrial chemicals from biomass is an important step toward mitigating climate change.

The chemical industry has to recognize that continuing the use of nonsustainable feedstocks to manufacture industrial chemicals is not a viable option, especially with the growing concerns about climate change. Utilizing the existing chemical industry and simply using feedstocks derived from biomass is the most economical and expedient way to accomplish two major goals: make the chemical industry more sustainable and slow the increase in the atmospheric carbon dioxide concentration. Eventually, it will be a strategy to avoid carbon taxes on the top 100 industrial chemicals.

In this paper, a systematic method of generating the reaction pathways from various biomass sources to the top 100 industrial chemicals, which maximize the overall carbon economy, was presented. It provides a listing of multiple ways of manufacturing the industrial chemicals in the order of deceasing-carbon economy.