RSC Advances
Page 1 of 5Journal Name
DOI: 10.1039/C5RA12375E
Cite this: DOI: 10.1039/c0xx00000x
COMMUNICATION
Nano porous hydroxyapatite as a biꢀfunctional catalyst for bioꢀfuel
production†
Nagabhatla Viswanadham, ab
Ala'a H. AlꢀMuhtasebc
*
Suman Debnath,a Peta Sreenivasulu,a Devaki Nandan,a Sandeep K Saxena,ac
5
Received (in XXX, XXX) Xth XXXXXXXXX 20XX, Accepted Xth XXXXXXXXX 20XX
DOI: 10.1039/b000000x
55 huge amount of water.8,9 Esterification with low molecular
weight acids, transesterification with low molecular weight esters
and acetalization with aldehydes or ketones are the other
promising and economically viable alternative routes for the
conversion of glycerol.10ꢀ14
60 Acetalization with ketones, especially acetone is gaining
importance due to the fact that acetone is widely produced from
biomass conversion as well as from the chemical process of
cumene cracking. Hence, facilitating reaction between two
biomass derived products glycerol and acetone is advantageous as
Nano
porous
hydroxyapatite
possessing
acidꢀbase
functionality has been successfully synthesized by a simple
10 hydrothermal method using P123 triꢀblock coꢀpolymer as
structure directing agent. The material exhibited excellent
catalytic activity for the production of solketal (100%
selectivity) from bioꢀglycerol (90% conversion)
15 Calcium phosphate compounds are of vital importance due to
their biochemical nature such as in bone formation and their long
time stability.1 Synthesis of high quality calcium phosphates is of
considerable interest for its applications in important areas of 65 they constitute an excellent component for the formulation of
2
biology, medicine and geology. Hydroxyapatite (HAP) is the
20 most stable among the known calcium phosphates and hence
suitable for exploring for various applications.3 The material with
gasoline, diesel and biodiesel fuels.15,16 These oxygenated
compounds, when incorporated into standard diesel fuel, have led
to a decrease the undesired emissions of particles, hydrocarbons,
carbon monoxide and aldehydes. Likewise, these products also
its general composition of Ca10 (PO4)6(OH)2 possesses a special
property of exhibiting both acid (PO4 ion) and base (Ca+2 ion) 70 can act as improvers of cold flow and flash point properties of
ꢀ2
active sites together. Due to this reason, the material has been
25 recently gaining special importance in catalysis for selective
reactions where the synergetic functioning of acidꢀbase active site
pair facilitates the molecular transformations.4 The tunable ratio
biodiesel along with simultaneous reduction its viscosity
desirable for fuel applications.17
Continuous processes for the formation of solketal employing
heterogeneous catalysts, such as the commercial macro porous
of Ca/P in on one hand and the presence of ion exchange 75 acid resins of the Amberlyst family, have been described in the
positions at Ca, PO4 and OH regions of the material on the other
30 make it convenient for the synthesis of wide variety of acidꢀbase
pair, metal functionalized materials.5 With their flexibility in
properties the materials have been successfully employed for
literature. More recently, G. Vicente et al.6 reported the suitability
of sulphonic mesoꢀstructured silica as a catalyst for the
acetalization of glycerol. The acid functionalized CꢀSi composite
materials have also been successfully employed for acetalization
various reactions such as oxidation of alkanes, water gas shift 80 of glycerol and to the best of our knowledge, acidꢀbase
reaction, Knoevenagel condensation, FriedelꢀCrafts alkylation
35 reaction, dehydrogenation and dehydration of alcohols.4ꢀ7
The production of oxygenates from glycerol gains much
importance due to the excellent dieselꢀblending property of the
functionalized materials have not been studied for this reaction.
On the other hand, the acidꢀbase site bearing HAP has been used
as a catalyst for dehydrogenation and hydrogen transfer reactions
of alcohols, and for catalytic intraꢀmolecular dehydration of lactic
oxygenates that not only improve the quality of the fuel but also 85 acid to acrylic acid. In the present study, the lab synthesized nano
increases the overall yield of the biodiesel. This reaction also
40 helps to meet the target for energy production for transport from
renewable sources. Olefins such as isobutene or alcohols such as
tertiary butyl alcohol are commonly used as etherifying agents of
glycerol. But the use of olefins create the problem of undesired
diꢀolefin formation, while the alcohols can cause the formation of
45
particles of HAP (CaP) material possessing both acid and base
sties has been first time employed for the interꢀmolecular
dehydration (condensation) from glycerol and acetone to produce
solketal at solventꢀfree reaction conditions.
Herein we report a simple hydrothermal method for the
synthesis of crystalline calcium phosphate nano particles
exhibiting acidꢀbase dual functionality suitable for effective
catalytic applications related to biomass conversion by using
P123 triꢀblock copolymer (Poly (ethylene glycol)ꢀpoly (propylene
95 glycol)ꢀpoly (ethylene glycol) (EO20ꢀPO70ꢀEO20) as an organic
template . The typical synthesis method involves (ESI) the
admixing of P123 block coꢀpolymer, 1N HCl, ammonium
dihydrogenphosphate, methanol followed by stirring of the
resultant mixture at 60 °C for 2 hr until the formation of a clear
90
aAcSIRꢀIndian Institute of Petroleum Dehradun, India.
bCatalysis and Conversion Processes Division, Indian Institute of
Petroleum, Council of Scientific and Industrial Research, Dehradunꢀ
248005, India, Fax: 91ꢀ135ꢀ2525702, Tel: 91ꢀ135ꢀ2525856, Eꢀmail:
c Department of Petroleum and Chemical Engineering, Sultan Qaboos
University,Muscat 123, Oman
†Electronic supplementary information (ESI): Experimental details, wide
angle XRD, EDX, SEM images, IR spectra, TG/DTA, TPD etc.
This journal is © The Royal Society of Chemistry [year]
[journal], [year], [vol], 00–00 | 1