520
4 Value-Added Products from Alcohols
Abundant availability of nearly complete range alcohols, at low cost, derived mostly
from renewable biomass resources, has provided a great impetus for the development of a number of catalytic processes for their conversion into value-added products. Processes for the manufacture of whole range of chemicals that include
building block chemicals (olefins and aromatics), oxygenates (aldehydes, ketones,
acids, ethers, esters, amides) and fuels (gasoline, diesel, jet fuel and fuel additives)
with alcohols as feedstocks have been explored, thus making them as the most versatile group of platform molecules. Salient features of such processes and advances
therein are described in the following pages. However, well-established applications
of alcohols like conversion of methanol to formaldehyde, acetic acid and MTBE are
not covered.
4.1 Conversion of Methanol to C 2 –C 3 Olefins
Global demand for ethylene and propylene is estimated as 152 MMT (million metric tons) and 102 MMT, respectively, in 2017 and is projected to reach 185 MMT
and 127 MMT by 2022 [139]. Building block olefins like ethylene and propylene
along with 1,3-butadiene and butenes (1-, 2- and iso-) are the raw materials for commodity petrochemicals and polymers, and the current dominant route for manufacturing is by highly energy-intensive thermal steam cracking (SC), using
non-renewable fossil-based raw materials, ethane/propane or naphtha.
Methanol to olefins (MTO) process developed by UOP-Hydro [140] provided the
first commercially viable alternative route for SC process. Based on the tailor-made
SAPO-34 catalyst [141–143], the process operates in the temperature range
340–540 °C at 0.1–0.3 MPa pressure, in a fluidized bed reactor (Fig. 11) coupled
with catalyst regenerator, considering the deactivation characteristics of the catalyst
[144]. Appropriate pore size (3.8 Å), to minimize the formation of higher carbon
number products, and optimized acidity, to control the formation of paraffins by
hydride transfer, are the key catalyst characteristics responsible for 75–80% carbonbased combined selectivity towards ethylene and propylene. By varying the process
conditions, maximization of ethylene or propylene yield could be achieved. Besides
ethylene and propylene, small amounts of C 4 –C 6+ olefins are generated. In the
advanced version of the process, Olefins Cracking (OC) process technology, developed by Total Petrochemicals [145], which involves routing the by-product C 4 –C 6+
olefins stream through a catalyst bed for further cracking to ethylene and propylene,
was integrated with MTO process. This additional process step increases the overall
yield of ethylene and propylene and reduces by-products’ formation.
With further modifications in the catalyst formulation to maximize propylene,
propylene/ethylene ratio >2 (Fig. 12) could be achieved [146]. Similar MTO processes, D-MTO and D-MTO-II (from Dalian Institute of Chemical Physics, DICP,
R. Vinayagamoorthi et al.
4 Value-Added Products from Alcohols
Abundant availability of nearly complete range alcohols, at low cost, derived mostly
from renewable biomass resources, has provided a great impetus for the development of a number of catalytic processes for their conversion into value-added products. Processes for the manufacture of whole range of chemicals that include
building block chemicals (olefins and aromatics), oxygenates (aldehydes, ketones,
acids, ethers, esters, amides) and fuels (gasoline, diesel, jet fuel and fuel additives)
with alcohols as feedstocks have been explored, thus making them as the most versatile group of platform molecules. Salient features of such processes and advances
therein are described in the following pages. However, well-established applications
of alcohols like conversion of methanol to formaldehyde, acetic acid and MTBE are
not covered.
4.1 Conversion of Methanol to C 2 –C 3 Olefins
Global demand for ethylene and propylene is estimated as 152 MMT (million metric tons) and 102 MMT, respectively, in 2017 and is projected to reach 185 MMT
and 127 MMT by 2022 [139]. Building block olefins like ethylene and propylene
along with 1,3-butadiene and butenes (1-, 2- and iso-) are the raw materials for commodity petrochemicals and polymers, and the current dominant route for manufacturing is by highly energy-intensive thermal steam cracking (SC), using
non-renewable fossil-based raw materials, ethane/propane or naphtha.
Methanol to olefins (MTO) process developed by UOP-Hydro [140] provided the
first commercially viable alternative route for SC process. Based on the tailor-made
SAPO-34 catalyst [141–143], the process operates in the temperature range
340–540 °C at 0.1–0.3 MPa pressure, in a fluidized bed reactor (Fig. 11) coupled
with catalyst regenerator, considering the deactivation characteristics of the catalyst
[144]. Appropriate pore size (3.8 Å), to minimize the formation of higher carbon
number products, and optimized acidity, to control the formation of paraffins by
hydride transfer, are the key catalyst characteristics responsible for 75–80% carbonbased combined selectivity towards ethylene and propylene. By varying the process
conditions, maximization of ethylene or propylene yield could be achieved. Besides
ethylene and propylene, small amounts of C 4 –C 6+ olefins are generated. In the
advanced version of the process, Olefins Cracking (OC) process technology, developed by Total Petrochemicals [145], which involves routing the by-product C 4 –C 6+
olefins stream through a catalyst bed for further cracking to ethylene and propylene,
was integrated with MTO process. This additional process step increases the overall
yield of ethylene and propylene and reduces by-products’ formation.
With further modifications in the catalyst formulation to maximize propylene,
propylene/ethylene ratio >2 (Fig. 12) could be achieved [146]. Similar MTO processes, D-MTO and D-MTO-II (from Dalian Institute of Chemical Physics, DICP,
R. Vinayagamoorthi et al.