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Assessing the sustainability and performance of green surfactants
04 March 2020IHS Markit Chemical Expert
As sustainability targets have become integral to corporate
strategies and consumers take a greater interest in the impact of
formulations on themselves and the environment, we're often asked
about the market for green surfactants. The answer is usually "it
depends," based on your understanding of the term "green." The
concept of green chemistry encapsulates various elements of
natural, bio-based, renewable, bio-degradable, and sustainable
concepts, both interms of raw materials and production
processes.
Surfactants are an important class of chemicals with
applications in household detergents and cleaners, personal care
and cosmetics, industrial and institutional cleaning, and an array
of industrial processes. The 2019 global market for surfactants,
worth an estimated $39 billion, is expected to grow at 2.6% per
annum over the next five years to reach $46 billion by 2024. The
industry produces over 17 million metric tons of surfactants
annually, some of which comes into personal contact with consumers
and much of which is ultimately discharged as effluent. Considering
this volume, addressing green issues is an important topic for an
industry facing increasing legislation and consumer concern.
A vast array of surfactants is available, produced from natural
and petroleum-based feedstocks and combinations of both. In this
highly competitive market, price and efficacy remain key drivers.
Therefore, renewable feedstocks and process economics must compete
with petroleum feedstocks that often serve multiple markets beyond
surfactant production. Fatty alcohols and acids derived from
natural fats and oils - such as soya, palm and palm kernel,
rapeseed, sunflower, tallow, and coconut oils - are a major source
of feedstocks for the manufacture of surfactants. They also form
the cornerstone of the green contribution to the industry.
How Green is Green Enough?
There is much concern regarding the sourcing of natural oils,
especially tropical oils. While producers have joined organizations
such as the Roundtable on Sustainable Palm Oil (RSPO), there
remains considerable debate on the true cradle-to-gate impact of
land use for renewable chemical feedstocks. Interestingly, Clariant
launched its GlucoPure Sense surfactant in 2017 that uses European
sunflower oil rather than tropical-sourced oils. BASF has also
commercialized amphoteric betaine surfactants that use microalgae
oils derived from fermentation of sugar instead of coconut
oil-derived cocamidopropyl betaines for use in hair care
formulations.
In 2019, detergent alcohols using bio-based renewable feedstock
accounted for 80% of the 3 million metric tons produced. Synthetic
alcohols, produced predominantly from ethylene but also from
n-paraffins and coal-based Fischer Tropsch processes, still provide
cost-effective alternatives to natural feedstocks, especially in
regions where ethylene feedstocks are economical, such as the
United States. Companies are still investing in synthetic alcohol
capacity. For example, Sasol will start up a 160 kilo tons per
annum (kta) total capacity facility for Ziegler, alumina, and
Guerbet alcohols by early 2021. Recent expansions of linear alpha
olefin capacity in the United States and planned expansions in the
United States (ExxonMobil) and Saudi Arabia (INEOS) will seek value
from the full range of C4-C20+ olefins produced, including the
C12-C18 mid-cuts used for detergent alcohol production.
So, does this mean all renewable-based surfactants are green?
Most applications require further processing of biobased feedstocks
to include moieties that provide the functional properties of the
surfactant, resulting in a range of anionic, cationic, nonionic and
amphoteric products. Most of these processes involve the
incorporation of petroleum-based feedstocks or moieties that would
not necessarily be considered green. To help assess individual
green qualities, the European Commission of Standardization has
devised classifications for biosurfactants, including >95%
wholly biobased; 50-94% majority biobased; 5-49% minority biobased;
and <5% nonbiobased.
Consumer Demand Drives Change
Anionic and non-ionic surfactants together account for 88% of
total global surfactant consumption. Nonionic surfactants are
dominated by alcohol ethoxylates (AE), which are used across the
spectrum of household, personal care, institutional, and industrial
applications. Sorbitan esters, such as sorbitan monostearate, are
produced from fatty acids and sorbitol. They represent an important
class of non-ionic surfactants derived from renewable feedstocks
that are typically used in food and cosmetic applications for their
emulsifying properties. Anionic surfactants are dominated by
petroleum-based linear alkyl enzene sulfonates, but they also
include major products such as alcohol sulfates (AS) and alcohol
ether sulfates (AES). AS and AES are produced by sulfation of the
corresponding alcohol or its ethoxylate with sulfur trioxide or
chlorosulfonic acid followed by neutralization. A fatty alcohol
sulfate consequently may have a renewable carbon index of 100% but
may not be considered by consumers to be particularly natural or
green. Alcohol ether sulfates are predominantly used in personal
care and household dishwashing liquids, where the ethoxylation is
milder than the alcohol sulfates that are known to irritate skin.
Despite this, consumers are increasingly looking to formulations
that are completely sulfate-free.
Cationic surfactants such as fatty amines and quaternary
compounds are largely used in fabric softeners, while mild
amphoteric surfactants such as cocoamidopropyl betaines are mainly
used in personal care products. Together they only contribute 12%
of the total surfactant consumption by volume.
AE and AES are produced by reacting alcohols, most commonly in
the C12-C16 range, with ethylene oxide (EO). They provide products
with a wide range of molar ratios of EO to detergent alcohol.
Obtaining a 100% renewable carbon index for AE and AES requires the
EO moiety to be derived from bio-ethylene oxide, which in turn is
derived from bioethanol that is usually produced from sugar cane,
via bioethylene.
Numerous bio EO plants exist, although they represent less than
2% of the total EO global production. The largest plants have
traditionally focused primarily on the manufacture of bio ethylene
glycol. In 2017, Croda International commissioned the first
bioethylene oxide unit in North America at Atlas Point and began
offering its so-called "ECO range" of ethoxylated surfactants.
However, the company has not operated the bio-EO unit consistently
since its commissioning. There are several bioethylene oxide plants
in China of similar design and scale (30-75 kta EO) as the Croda
unit. These plants were mostly built to eliminate long and
expensive supply chains for EO, but they also can tout the benefit
of offering bio-based products. It is important to note that
bioethylene oxide has higher cash cost of production than
petrochemical-based processes, due to smaller unit scale and
generally higher-cost raw material, bio-ethanol.
High Demand, Low Availability
Personal care applications represent 14% of the total volume
consumption of surfactants but will experience higher than average
global growth rates of 3.1% over the next five years. They also can
offer greater opportunities for green surfactant solutions.
Consumers are increasingly discerning regarding products that
contact skin, such as shampoos, shower gels, soaps, cosmetics, hand
dishwashing products, and household cleaners. Personal care
applications also offer greater opportunities for producers to meet
consumer demands for more natural ingredients.
The use of glucose moieties in combination with fatty alcohols
offers a range of surfactants that have found commercial success,
particularly in the personal care and hand-dishwashing markets.
Alkyl polyglucosides (APGs) produced by companies such as BASF,
Nouryon, and SEPPIC and alkyl glucamides produced by companies such
as Clariant have shown tremendous growth over the last five years.
Their natural appeal, low toxicity, and effective surfactant
properties boosted growth rates above those seen for traditional
surfactants. In November 2019, BASF announced expansion of its
production capacity for APG at Jinshan, China. Further expansions
are planned to meet growing domestic demand and relieve pressure on
its facility in Germany. Total global consumption of APGs is now
estimated at around 140kmt (100% active).
Sugar feedstocks also provide the basis for a range of amino
acid-based surfactants, such as disodium cocoyl glutamate. These
anionic surfactants are used in cosmetic and personal care products
where mild, natural, sulfate-free ingredients are increasingly
valued by consumers. Ajinomoto, a major producer of amino
acid-based surfactants, this year announced expansion of its
Amisoft® glutamates capacity at a new plant in Brazil, to be
commissioned in 2020.
Green surfactants offer an important, growing contribution to
the industry - although the size of the contribution can vary
depending on perceptions what is natural, bio-based, and
sustainable. Furthermore, while many personal care and consumer
goods companies have expressed interest in 100% bio-based
surfactants, the market has not so far tested consumers'
willingness to pay premium prices for otherwise commodity products.
This is due to lack of widespread availability of green commodity
surfactants to date as much as any other consideration. It is clear
that global demand for both petroleum- and bio-based surfactants
will continue to grow with increasing hybridization of formulations
to meet consumer, legislative, and sustainability demands - all
while challenging manufacturers to balance cost-effective
formulations with the ability to perform effectively.
Adam Bland | Executive Director - Solvents
& Surfactants, IHS Markit