1. Hydroprocessing of diesel and vegetable oil blends
T.M. Sankaranarayanan, M. Banu,
A.K. Tiwari and S. Sivasanker
National Centre for Catalysis Research,
Indian Institute of Technology - Madras,
Chennai
NCCR3rd Annual day 01st Aug 2009

2. CARBON NEUTRAL BIO-MASS BASED FUELS
INTRODUCTION
The use of fossil fuels at the present rate
is not sustainable due to:
Rapid depletion of resources
2) Carbon emission – global warming due to greenhouse gases (GHG)
USE RENEWABLE
and
CARBON NEUTRAL BIO-MASS BASED FUELS
Global fossil fuel consumption ~ 7 Gt/y
Biomass produced annually ~ 200 Gt/y
NCCR3rd Annual day 01st Aug 2009

3. OIL USE – SECTOR WISE (million tons, oil equivalent)
4300 54
3600 52
3200 50
2800 42
Total
Share of Transport
250
215
192
140
Other
1430
1265
1216
1340
Heating and Industrial
300
Petrochem.
2320
1870
1600
1180
Transport
2010
2000
1995
1985
Share of transportation sector is increasing
Replacing diesel & petrol with biofuels is important for
sustainable growth
NCCR3rd Annual day 01st Aug 2009

4. "The use of vegetable oils for engine fuels may seem
Rudolf Diesel
(1858 – 1913)
His first engine ran on
peanut oil (1900, Paris)
"The use of vegetable oils for engine fuels may seem
insignificant today. But such oils may become in the
course of time as important as the petroleum
and coal tar products of the present time" Rudolf Diesel, 1912.
NCCR3rd Annual day 01st Aug 2009

5. Disadvantages of neat vegetable oils as diesel fuel
Compared to diesel, vegetable oils possess
Higher viscosity (difficulty in feed injection)
Lower cetane number (poor engine performance)
Lower heating value (lower energy output)
High cloud and pour points (limited use in winter)
Lower stability due to unsaturation (tank deposits)
Larger carbon deposition in engine (engine damage)
Contain many impurities - phospholipids
Hence, vegetable oils are converted into FAME (Fatty Acid Mono Esters; biodiesel) by transesterification with methanol
They (FAME) are generally not used as neat fuels, but are blended (5 - 20%) with diesel and used.
NCCR3rd Annual day 01st Aug 2009

6. Diesel-FAME blends also have many drawbacks These are:
Expensive transesterification process (cost of fuel increases)
Need for conversion of by-product glycerol into value added
chemicals
3) Environmental effects of transesterification (waste disposal;
water requirement for washing etc.)
4) Lower heating value of the fuel (power output; tank capacity)
5) Compatibility problems of some components in the engine (cost)
Also, transesterification is not possible with conventional base
catalysts if free fatty acids are present in the oil (non-edible oils)
– these oils require expensive fatty acid separation or use of less
effective (or expensive) acid catalysts
NCCR3rd Annual day 01st Aug 2009

7. Other options for converting vegetable oils into diesel range fuels
Diesel fuel is a mixture of hydrocarbons (majority paraffins)
mostly in the carbon number range of 15 – 22.
Vegetable oils are triglycerides of mostly C16 and C18 fatty acids
Hence, they can be cracked / hydrocracked into diesel range
hydrocarbons
Many reports of cracking and hydrocracking of vegetable
oils into hydrocarbons are available in the literature. Presently,
there are no commercial processes for economic reasons
Cracking:
Cracking of neat vegetable oils produces poor quality products
and catalyst stability is poor; yield is also low
Hydrocracking:
Hydrocracking of neat vegetable oils requires high pressures
(>150bars) for complete conversion and is an expensive process

8. Another option is to blend the vegetable oil with the diesel
and hydroprocess at low severity conditions

9. We now present our preliminary studies on the
hydroprocessing of blends of a straight run
diesel oil fraction and a commercial
Sunflower oil over a zeolite containing
Ni-Mo-alumina catalyst
The objective of this study is to investigate the
cracking and hydrogenation of triglyceride
molecules blended with diesel into hydrocarbons
(C17 and C18 paraffins) under the moderate process
conditions typically used in the hydro-
desulfurization (HDS) of Straight Run diesel
[pressure: 60 bars or less, temp.: 350C or less]
NCCR3rd Annual day 01st Aug 2009

10. Feeds used: EXPERIMENTAL Chennai Petroleum Corporation Ltd. (CPCL)
Diesel: A straight run diesel fraction supplied by
Chennai Petroleum Corporation Ltd. (CPCL)
Vegetable oil: A commercial sunflower oil
Blends: 1) 80:20 and 2) 60:40 by wt, diesel: sun-
flower oil, 3) 90:10 diesel: Oleic acid and
4) 80:10:20 diesel, oleic acid and oil
The properties of the feeds are presented in the following slides
NCCR3rd Annual day 01st Aug 2009

11. Distillation characteristics
Properties of the straight run diesel fraction
Distillation characteristics
Property
Value
Source
PG mix
Density at 15C, g/cc
0.8610
Viscosity at 40C, cSt
5.03
Pour point, C
Aniline point, C 74
Flash point, C
121
Non-aromatics, wt%
58.5
Aromatics, wt%
41.5
Sulfur (N), ppm
17600 (140)
IBP
233C
IBP C
90%
371C
90% C
92.8%
380C
95% C
ASTM, D86
GC Sim. Dist., D2887

12. Gas chromatograms of the feeds used
Straight run diesel
Diesel fraction
C18
C17
C16
C20
C15
C24
C28
C32
C36
C40
C14
C12
C11 10 20 30 40 50 5 15 25 35 45
n-paraffins
Standard n-paraffins
NCCR3rd Annual day 01st Aug 2009

13. The fatty acid composition of the sunflower oil was established
20% vegetable oil blend
10% FFA (oleic acid) with diesel
C18 fatty acid
Vegetable oil
Diesel oil
Diesel oil
The fatty acid composition of the sunflower oil was established
by esterification with methanol and GC analysis of the esters.
Composition of the vegetable oil used (wt %):
C16 acids %
C18 acids - (0.538% steric, 22.38% oleic and 70.54% linoleic)

14. 2. Catalyst: A Ni-Mo-alumina-zeolite beta was used as the catalyst.
The composition (wt% on dry basis) of the catalyst was NiO (3), MoO3 (12), beta (30) and alumina (55).
The catalyst was prepared by the following sequence of operations:
Preparation of extrudates of alumina (from Plural SB; Sasol) and zeolite beta (Zeolyst International); drying /calcining
Impregnation of MoO3 (from ammonium heptamolybdate); drying /calcining
Impregnation of NiO (from Ni(NO3)2); drying /calcining
The characteristics of the catalyst are presented in the following slide
NCCR3rd Annual day 01st Aug 2009

15. Total pore volume (cm3/g)
Physicochemical characteristics of the catalyst
Sample
BET Surface area (m2/g)
Total pore volume (cm3/g)
Acidity (mmol/g)*
Weak
Strong
Total
Al2O3
212
0.60
0.056
0.098
0.154
BEA
580
0.55
0.236
0.042
0.278
Support (30% BEA -55% Al2O3)
282
0.49 -
12%MoO3, 3% NiO/Support
213
0. 40
* From TPD of NH3; weak and strong refer to amount of NH3 desorbed
below 200C and above 200C, respectively.
NCCR3rd Annual day 01st Aug 2009

16. 3. Catalytic experiments:
The hydroprocessing of the blends was carried out at different
process conditions in a high pressure fixed bed reactor
using 30 g of catalyst.
The process parameter ranges used were:
Temperature, C,
Pressure, 30 – 60 bars,
WHSV, 1 – 4 h-1 and H2/oil ratio, 500v/v.
The catalyst was presulfided with a DMDS/diesel feed
(2.5 wt % S) at 330C prior to carrying out the catalytic studies.
Product analysis was done in a GC (Perkin-Elmer)
using a short metal capillary column used for
simulated distillation analysis.
Analysis of the gaseous products were done in a GC (Mayura)
using molecular sieve and Hysep columns.

17. i. Products expected from the vegetable oil
RESULTS AND DISCUSSIONS
i. Products expected from the vegetable oil
Different products are expected from hydrocracking
of a typical triglyceride molecule depending on which bonds are cracked.
The likely products are:
1) C17 n-paraffin, 2) C18 n-paraffin, 3) C18 fatty acids, 4) C18 alcohol,
5) propane and 6) CO2.
NCCR3rd Annual day 01st Aug 2009

18. The triglyceride molecule itself may crack into di- and monoglycerides
The fatty acids formed are expected to undergo
hydrogenation into the alcohols and paraffins
Negligible olefinic products are expected at the
experimental conditions (high pressures of H2)
Cracking/isomerization may occur at the olefinc bonds producing light hydrocarbons and isomerized products
Products from C16 fatty acids will also be present (about 6.5%) - C16 and C15 hydrocarbons
NCCR3rd Annual day 01st Aug 2009

19. ii. Experiments with straight run diesel
Before carrying out studies with the diesel-vegetable oil blends, experiments
were done with the straight run diesel alone.
The diesel feed underwent mild hydrocracking depending on the operating conditions
About 4% cracking of the feed into lighter components (<IBP) was noticed at 340C,
60 bars pressure and WHSV (h-1) 2.
A small boiling point reduction as a result of cracking / isomerization / hydrogenation
of the heavier ends took place (typical data are shown below)
Temp oC
WHSV
(h-1) P
(Bar)
H2 (v/v)
Mass
balance
 Temp, oC
IBP
90 %
95 %
FBP
340 2 60
500 97
1.0
7.81
6.35
2.10
Feed Diesel
IBP
90%
95%
FBP
132.51
396.86
414.77
456.27
Gas chomatograms of some typical products of the reaction with the different feeds are presented in the next slide

20. iii. Gas chromatograms of some typical products
Diesel
320C, WHSV (h-1), 1
60 bars; H2/oil, 500 v/v
C17 & C18
20% oil blend
320C, WHSV (h-1), 1
60 bars; H2/oil, 500 v/v
Light
fraction
Light
fraction
C17
C18
40% oil blend
320C, WHSV (h-1), 4
30 bars; H2/oil, 500 v/v
Mono?
Di?
triglycerides
C18 acid

21. iv. Effect of temperature
Conversion
Diesel yield
Pressure = 60 bar
WHSV = 1 h-1
20% blend
40% blend
WHSV = 2 h-1
In the case of the 20% blend, the oil is completely converted into hydrocarbons
even at 320C at WHSV (h-1) = 1 and 60 bar pressure
In the case of the 40% blend, conversion of the oil is complete at WHSV (h-1) 1
and not at WHSV (h-1) 2.
At 60 bars pressure, only a trace amount of free fatty acid is seen in the
chromatogram at WHSV (h-1) = 2 and 320C.

22. v. Effect of feed rate (WHSV)
Yield
Conversion
Yield
Conversion
20% oil blend
320C, 60 bars;
H2/oil, 500 v/v
40% oil blend
320C, 60 bars;
H2/oil, 500 v/v
As expected, conversion of vegetable oil decreases with feed rate.
The effect is more noticed in the case of 40% blend.
Some free fatty acids are seen in the chromatograms of 40% blend at
higher flow rates (WHSV 2 & 4 h-1)

23. Higher pressures increase conversion and diesel yield
vi. Effect of pressure
Temp. = 320oC; WHSV (h-1) = 2; H2/oil = 500v/v
Yield
Yield
Conversion
Conversion
20% blend
40% blend
Yield
Conversion
10% oleic acid blend
Higher pressures increase conversion
and diesel yield
10% oleic acid blend is fully converted
even at 30 bars pressure
NCCR3rd Annual day 01st Aug 2009

24. vii. Conversion of free fatty acids
The following two blends of diesel with oil and free fatty acid (oleic acid) were prepared:
Diesel (70%) + Oil (20%) + oleic acid (10%)
Diesel (90%) + oleic acid (10%)
The results of the studies are shown below in the table
Feed
(Diesel +)
Temp.
(C)
WHSV
(h-1)
Press.
(bar)
nC17/nC18
Conv.
(%)
Yield
10%FFA + 20% oil
320 1 60
0.691
98.8
97.2
10%FFA
0.503
100
97.4 2
0.637
97.3 45
0.643
96.0 30
0.678
95.0
It is found that the fatty acids are entirely converted into hydrocarbons
even at moderate conditions, 30 bar pressure, 320C and WHSV (h-1) = 1.
The cracking of the glyceride molecules into C17 paraffin is more rapid than
cracking of the acid
Hydrogenation of the acid is more affected by SV than cracking

25. are entirely converted over the catalyst.
Chromatograms (see below) of both the blends reveal that the free fatty acids
are entirely converted over the catalyst.
Temp.= 320oC ,Pressure = 60 bar and WHSV = 1 h-1
10%FFA with 20% blend
10% FFA with Diesel
NCCR3rd Annual day 01st Aug 2009

26. viii. Ratio of C17 and C18 hydrocarbons
40% Blend
Temp.= 320oC
Pressure = 60 bar
H2/Oil = 500 v/v
20% Blend
40% Blend
10% Oleic Acid Blend
Pressure = 60 bar
WHSV = 2
H2/oil = 500v/v
NCCR3rd Annual day 01st Aug 2009

27. Ratio of C17 and C18 hydrocarbons
10%Oleic acid blend
40% Blend
20% Blend
Temp.= 320
WHSV = 2
H2/Oil = 500 v/v
Increase in temperature / feed rate increases C17formation
Increase in pressure decreases C17 formation; the effect is not significant in the
case of the FFA blend
NCCR3rd Annual day 01st Aug 2009

28. C17 paraffin is formed from two sources: glycerides and C18 acid
Based on the hydrocracking of the oil and FFA blends and the
products obtained in the reaction, the following conclusions are reached:
C17 paraffin is formed from two sources: glycerides and C18 acid
C17 paraffin is formed from C18 acid by decarbonylation and
from glycerides by the cracking of the –C(=O)---C17 bonds
C18 paraffin is formed from C18 acid by hydrogenation
NCCR3rd Annual day 01st Aug 2009

29. Temperature increases cracking of the –C(=O)---CH2 bond in
the glycerides
Higher pressures increase hydrogenation of the C18 acid and
cracking (hydrogenolysis) of the -C---O- bond (ether linkage) in
Increasing the feed rate decreases hydrogenation relative to
cracking of the acid; also increases cracking of –C(=O)---CH2
bond compared to -C---O- bond
Other observations:
Only traces of di- and monoglycerides were detected (?)
Glycerol and the alcohol could not be identified (?)
Light hydrocarbons could also be formed by cracking of
hydrocarbons and others
Based on the above conclusions and observations, the following
scheme for the cracking of triglycerides is proposed

30. ix. Conversion pathways for the oil
The studies and the products obtained suggest the following pathway for the
conversion of the oil
Triglyceride
Diglyceride
C18 alcohol
C17 paraffin
Monoglyceride
C18 paraffin
Glycerol
Propane
CO2 +
C18 acid
Further studies to understand the mechanism of the individual steps in the
reaction are in progress

31. x. Hydrodesulfurization (HDS) activity
Composition (S, wt%)
Conditions
HDS % (S in product, %)
20 % blend (1.408%)*
320C,60 bar P, WHSV=1
64.66 ( )
330C,60 bar P, WHSV=1
72.52 (0.3868)
340C,60 bar P, WHSV=1
86.05 ( )
350C,60 bar P, WHSV=1
91.12 (0.1249)
40% blend (0.704%)*
51.97 (0.3381)
320C,60 bar P, WHSV=2
22.96 (0.5423)
320C,60 bar P, WHSV=4
17.89 (0.5780)
Diesel (1.76%)
75.48 (0.4314)
* Calculated assuming zero S in the vegetable oil
Regarding the desulfurizability of the feeds, It is found that at similar
conditions, % S-removed from the feeds is nearly the same for both
diesel and for diesel + oil blends (at least for 20% blend)
As expected, % HDS increases with temperature and decreases with
feed rate for the blends
NCCR3rd Annual day 01st Aug 2009

32. xi. Conclusions
It is possible to transform diesel-vegetable oil (20%) blends at relatively moderate operating HDS conditions into a pure hydrocarbon fuel
Zeolite beta is a suitable acidic hydrocracking component for the reaction.
The catalyst is expected to possess a long life – the catalyst has not deactivated for more than 200 hours of operation
An advantage of the process is that it can also be used in the case of non-edible vegetable oils containing free fatty acids.
The processing of vegetable oil and diesel blend can be carried out during the HDS of the diesel provided a suitable catalyst is used
NCCR3rd Annual day 01st Aug 2009

33. Thank you
NCCR3rd Annual day 01st Aug 2009