**3. Routes for glycerol conversion**

The annual production of biodiesel worldwide has increased in the last two decades. As a result, a large amount of the surplus crude glycerol has been generated. Currently, 90% of glycerol is produced from biodiesel [8] through the reaction of transesterification, which produces biodiesel and glycerol at mass ratio of 10: 1, i.e., for every 10 kg of biodiesel, 1 kg of crude glycerol is produced [11].

The glycerol produced from transesterification contains several impurities, such as: water, soaps, fatty acids and their esters, methanol and catalyst, usually sodium or potassium hydroxide. The removal of these impurities is necessary for the application of glycerol in different kind of industries, such as pharmaceutical, food and cosmetics [8]. Glycerol must reach a specific purity depending on its application, and also on the specification of the contaminants that must be removed through more sophisticated separations [12]. For pharmaceutical industries, glycerol must reach USP (United States Pharmacopeia) grade, which contains 99.5% by weight, while for applications in the food industry, the FCC (Food Chemical Codex) grade is required, with 99.7% by mass [13]. In addition, for application in the production of high added-value molecules, the impurities must be removed as they can significantly inhibit bacterial growth and fermentation (biotechnological processes) or the activity of heterogeneous catalysts (chemical processes) [14].

Glycerol can be converted into chemicals by several different reactions, such as oxidation, dehydration, hydrogenation, acetylation, esterification, etherification, ammoxidation, among others, as shown in **Table 1** [7, 14, 15].

As shown in **Table 1**, several studies have been carried out to convert glycerol into value-added chemicals through catalytic routes. For each reaction, specific homogeneous and heterogeneous catalysts were studied as an active phase, which is responsible for promoting the conversion of glycerol. Although glycerol is a promising alternative to reduce the dependence or even replace conventional production of petrochemical products [14], the good selectivity to desired products at high conversions is still a technological barrier. This is due to glycerol hydroxyls to have similar reactivity, unknown reaction conditions and the lack of efficient catalysts [7].

**191**

**4. Economic analysis**

*Sources: Adapted from [2, 7, 14].*

*High added-value chemicals from glycerol.*

**Table 1.**

**4.1 Glycerol**

*Market Prospecting and Assessment of the Economic Potential of Glycerol from Biodiesel*

acid, oxalic acid, mesoxalic acid, propionic acid, acrylic acid, citric acid, succinic acid,

hydroxypropane, propanaldehyde, adducts, acetone, dihydroxyacetone and polyaromatic

1,2-Propanediol, 1,3-propanediol, propanol, ethylene glycol, lactic acid, acetol,

1,3-di-tert-butyl glycerol, 1,2-di-tert-butyl glycerol and 1,2,3-tri-tert-butyl glycerol,

Acetylation Acetins (glycerol mono-, di- and triester) ZrO2/SiO2/ME, ZrO2/SiO2/SG,

Oxidation Glycolic acid, hydroxypyruvic acid, tartaric

Dehydration Acrolein, acetaldehyde, hydroxypropanone,

dichloro-2-propanol

Esterification Mono, di and tri glycerates, glycerol carbonate, polyesters and branched nylons

Etherification Glycerol tert-butyl ether, methyl butyl ether,

fumaric acid

compounds,

**Chemical derivatives Catalysts and active phases**

Pt/C, Pd/C and Au, Pt-Bi

SiO2/Al2O3, ZnSO4 H2SO4, H3PO4/ (TiO2 and

Pt, Pd, Rh and Ru Ni and Cu

HClSO3/ZrO2 S-ZrO2 and H2SO4/ZrO2

KOCH3

CH-SO3H La and Mg catalysts

Al, P, G and Nb

Al, V, Sb and Nb oxides

NaOH, KOH, NaOCH3,

Ru/S, CuCr2O4 and Cu/Zn

H3PW12O40/SiO2/C Niobic acid /ZrO2

catalysts

SiO2)

Zeolites

The production of 1,3-propanediol, acrylic acid and acrylonitrile are promising products from glycerol. 1,3-propanediol has great economic potential and a recent market, which can be expanded using glycerol as raw material, while acrylic acid and acrylonitrile come from consolidated petrochemical processes, which can be replaced by sustainable glycerol processes. In this context, it is important to evaluate the market and economics of these derivatives, in order to define a proposal for a

Amoxidation Acrylonitrile Mo, Bi, Sb, V, Sn, W, Zr, Ti, Ni,

Glycerol is found in the ITC under the codes SH6 1520.00 and 2905.45. SH 1520.00 refers to crude glycerol, water and glycerol lye. These nomenclatures present glycerol with different concentrations depending on the producing company or

The excess of crude glycerol has promoted a continuous decrease in its market value, reaching US \$ 170 / t in 2019. This is one of the main factors to enable the implementation of a process for the production of high added value product. As previously mentioned, the production of 1,3-propanediol, acrylic acid and acrylonitrile are promising products from glycerol. Currently, the industrial production of acrylonitrile and acrylic acid use propylene as raw material, which price was

potential process of production of these molecules from glycerol.

country and, therefore, the value of the final sale price is different.

*DOI: http://dx.doi.org/10.5772/intechopen.93965*

**Conversion of glycerol**

Hydrogenation/ Reduction

**Conversion of glycerol Chemical derivatives Catalysts and active phases** Oxidation Glycolic acid, hydroxypyruvic acid, tartaric acid, oxalic acid, mesoxalic acid, propionic acid, acrylic acid, citric acid, succinic acid, fumaric acid Pt/C, Pd/C and Au, Pt-Bi catalysts Dehydration Acrolein, acetaldehyde, hydroxypropanone, hydroxypropane, propanaldehyde, adducts, acetone, dihydroxyacetone and polyaromatic compounds, SiO2/Al2O3, ZnSO4 H2SO4, H3PO4/ (TiO2 and SiO2) Al, V, Sb and Nb oxides Zeolites Hydrogenation/ Reduction 1,2-Propanediol, 1,3-propanediol, propanol, ethylene glycol, lactic acid, acetol, dichloro-2-propanol Pt, Pd, Rh and Ru Ni and Cu Acetylation Acetins (glycerol mono-, di- and triester) ZrO2/SiO2/ME, ZrO2/SiO2/SG, HClSO3/ZrO2 S-ZrO2 and H2SO4/ZrO2 Esterification Mono, di and tri glycerates, glycerol carbonate, polyesters and branched nylons NaOH, KOH, NaOCH3, KOCH3 H3PW12O40/SiO2/C Niobic acid /ZrO2 Etherification Glycerol tert-butyl ether, methyl butyl ether, 1,3-di-tert-butyl glycerol, 1,2-di-tert-butyl glycerol and 1,2,3-tri-tert-butyl glycerol, Ru/S, CuCr2O4 and Cu/Zn CH-SO3H La and Mg catalysts Amoxidation Acrylonitrile Mo, Bi, Sb, V, Sn, W, Zr, Ti, Ni,

*Market Prospecting and Assessment of the Economic Potential of Glycerol from Biodiesel DOI: http://dx.doi.org/10.5772/intechopen.93965*
