Second-Generation Biofuels by Co-Processing Catalytic Pyrolysis Oil in FCC Units

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Applied Catalysis B: Environmental 145 (2014) 161–166

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Applied Catalysis B: Environmental

jo urnal homepage: www.elsevier.com/locate/apcatb

Second-generation biofuels by co-processing catalytic pyrolysis oil in FCC units

a a a,∗ a b b

N. Thegarid , G. Fogassy , Y. Schuurman , C. Mirodatos , S. Stefanidis , E.F. Iliopoulou ,

b b

K. Kalogiannis , A.A. Lappas

IRCELYON, Institut de recherches sur la catalyse et l’environnement de Lyon, Université Lyon 1, CNRS, UMR 5256, 2 avenue Albert Einstein, F-69626 Villeurbanne, France

Chemical Process and Energy Resources Institute, CERTH, P.O. Box 60361, Thermi, 570 01 Thessaloniki, Greece

a r t i c l e i n f o a b s t r a c t

Article history: Previous research showed that hydrodeoxygenated (HDO) pyrolysis-oils could successfully be co-

Received 9 November 2012

processed with vacuum gasoil (VGO) in a labscale ﬂuid catalytic cracking (FCC) unit to bio-fuels. Typically

Received in revised form 11 January 2013 ◦

the hydrodeoxygenation step takes place at ∼300 C under 200–300 bar of hydrogen. Eliminating or

Accepted 13 January 2013

replacing this step by a less energy demanding upgrading step would largely beneﬁt the FCC co-processing

Available online 4 February 2013

of pyrolysis oils to bio-fuels. In this paper a bio-oil that has been produced by catalytic pyrolysis (cat-

alytic pyrolysis oil or CPO) is used directly, without further upgrading, in catalytic cracking co-processing

Keywords:

mode with VGO. The results are compared to the co-processing of upgraded (via HDO) thermal pyrolysis

Renewable feedstock

Reﬁning oil. Though small but signiﬁcant differences in the product distribution and quality have been observed

between the co-processing of either HDO or CPO, they could be corrected by further catalyst develop-

Catalytic cracking

Biomass ment (pyrolysis and/or FCC), which would eliminate the need for an up-stream hydrodeoxygenation

ZSM-5 step. Moreover, the organic yield of the catalytic pyrolysis route is estimated at approximately 30 wt.%

compared to an overall yield for the thermal pyrolysis followed by a hydrodeoxygenation step of 24 wt.%.

1. Introduction and a large proportion (20–30 wt.%) of lignin-derived oligomers [5].

Due to their oxygen rich composition, they present a low heating

Due to the depletion of carbon fossil resources (oil, gas and value, immiscibility with hydrocarbon fuels, chemical instability,

coal) and increased efforts to mitigate CO2 emissions, the pro- high viscosity and corrosiveness [6–10], restricting their direct use

duction of liquid transportation fuels from biomass has become as fuels. The (partial) elimination of oxygen is thus necessary to

a booming research area [1]. Within the frame of the “20-20-20” transform the bio-oil into a liquid fuel that can compete with min-

objectives aiming to achieve 20% emissions reduction, 20% increase eral oil reﬁnery fuels. Two main types of upgrading processes are

of renewable energy and 20% increase in energy efﬁciency by 2020 used to reject oxygen from pyrolytic bio-oils: hydrotreating or

proposed by the EU, in close link with the the International Energy hydrodeoxygenation (HDO) and catalytic cracking. The former uses

Agency “Energy Technology Perspectives 2020”, a general consen- hydrogen to remove oxygen in the form of water from the initial

sus is to focus on bio-fuels that are not in net competition with thermal pyrolysis oil over mixed oxides and supported metal cata-

food production, and to reach the objectives for fuel transportation lysts. The latter accomplishes the removal of oxygen in the form of

either via blending or co-processing strategies. In that sense, non- water and carbon oxides, generally over acid catalysts (zeolites). An

competing lignocellulosic biomass sources derived from forestry obvious drawback of the HDO process is the use of large amounts

and industrial wastes seem to be the most realistic feedstock for of hydrogen at elevated pressures while catalytic cracking does not

the production of a second generation of transportation fuels [2]. require hydrogen. The latter leads to more oleﬁnic and aromatic

Lignocellulosic biomass can be converted to liquids by fast pyrol- products.

ysis [2,3]. This technology is currently in its pilot pre-industrial An alternative to post-pyrolysis upgrading processes is a com-

stage [3]. Pyrolysis-oils are composed of a very complex mixture of bined pyrolysis/deoxygenation step. The thermal pyrolysis step can

oxygenated hydrocarbons (> 300) [4], the main constituents being be combined with the catalytic cracking step in one operation by

acids, aldehydes, ketones, alcohols, glycols, esters, ethers, phenols replacing the silica sand in the ﬂuidized bed reactor by an appropri-

and phenol derivatives, as well as carbohydrates and derivatives, ate catalyst or by placing the catalyst directly in the freeboard space

of the reactor. This is referred to as catalytic pyrolysis [11–31].

Research studies on catalytic pyrolysis have appeared in the

∗ open literature regularly since the 1980s, but their number has

Corresponding author.

E-mail address: [email protected] (Y. Schuurman). increased signiﬁcantly during the last 5–6 years [11–31]. The KiOR

162 N. Thegarid et al. / Applied Catalysis B: Environmental 145 (2014) 161–166

Table 1 Table 2

Properties of VGO, HDO and CPO. P NMR analysis of the two bio-oils.

Property VGO HDO CPO HDO CPO

3 ◦

Density (g/cm , 25 C) 0.8953 0.9323 nd Hydroxyl groups (mmol/goil) 1.4 0.6

Sulfur (wt.%) 2.02 <0.01 <0.20 Phenolic groups (mmol/goil) 1.4 3.1

Nitrogen (wt.%) 0.07 <0.1 <0.10 Acidic groups (mmol/goil) 0.6 0.5

Hydrogen (wt.%) 12.4 10 7

Carbon (wt.%) 85.4 69 66

Oxygen (wt.%) Traces 21 27

of two fractions, an aqueous and an oil fraction. Only the organic

H2O (wt.%) Traces 3 11

fraction was used during the test. The density and elemental

composition of the ﬁnal CPO is reported in Table 1.

Phosphor NMR analysis allows to quantify the oxygenated com-

company has deposited a patent application on this process and is

pounds into three groups of alcohols, phenols and acids [42]. Table 2

operating a pilot plant in the USA [32].

shows these quantities for both bio-oils. Size exclusion chromatog-

The studies are difﬁcult to compare as there is a large variation

raphy (SEC) was used to compare the molecular weight distribution

of a number of parameters: biomass source (model compounds,

of the two bio-oils. Although the molecular weights should not

wood, corn etc.), scale of operation (micrograms to kilograms), con-

be taken as absolute values (polystyrene calibration), compari-

tact time, mode of contact between biomass and catalyst, biomass

son showed that HDO oil contains components up to 1700 g/mol

to catalyst ratio and the type of catalyst. Keeping this in mind some

whereas CPO components go up to 2600 g/mol.

general trends can be discerned:

An equilibrated industrial FCC catalyst containing ∼15 wt.% Y-

The addition of a catalyst to the thermal pyrolysis process results

zeolite was used for VGO cracking and co-processing experiments.

in a lower yield of bio-oil organic compounds. The lower oil yields

The equilibrated industrial FCC catalyst used in this study contains

stem from oxygen removal to water, CO2 and CO, to coke formation

15 wt.% Y-zeolite, 2.5 wt.% rare earth oxides, 240 ppm of Ni and

on the catalyst and to an increase in hydrocarbon gas yield.

870 ppm of V.

The yield of the oil fraction depends on the catalyst formu-

lation. In a large number of studies ZSM-5 is reported to give

the highest yield among other zeolites including commercial FCC 2.2. Set-up

(Fluid Catalytic Cracking) catalysts. Some bulk oxides, such as ZnO,

CuO, Fe2O3 are reported to be good catalysts as well [11]. In addi- VGO cracking and co-processing (VGO + CPO or HDO crack-

tion, mesoporous MCM materials have been studied extensively ing) experiments were performed in a ﬁxed-bed quartz reactor

[18,30,31]. The catalyst formulation not only has an effect on the (ID = 12 mm, L = 340 mm) containing 2.0 g of FCC catalyst at 1.2 bar

bio-oil yield, but it also inﬂuences its composition leading thus to and operated to mimic a series of FCC cycles. The equipment has

a better quality bio-oil. been validated with respect to a microactivity test reactor for VGO

This study reports on the co-processing of catalytic pyrolysis cracking [43]. A thermocouple was located inside the catalyst bed.

oil (CPO) with vacuum gasoil (VGO) in a Fluid Catalytic Cracking Argon was used as a carrier gas (ﬂow = 100 ml/min). One reaction

◦

(FCC) labscale unit. The results are compared to co-processing of cycle consists of 1 minute cracking at 500 C, 11 min of stripping

◦

HDO-upgraded thermal pyrolysis oil with VGO in FCC [33–35], in under argon ﬂow at 500 C, 40 min regeneration under 20 vol.% of

◦

order to assess the advantages and drawbacks of each upgrading O2 in Ar at 650 C and 11 min purge. In order to obtain sufﬁcient

strategy. FCC is one of the most important processes of a modern liquid for further analysis 6 reaction/regeneration cycles were per-

reﬁnery because of its ﬂexibility to changing feedstock and prod- formed for each run. During the cracking and stripping steps, the

uct demands. Its principal aim is to convert high molecular weight liquid product was collected in a glass receiver located at the exit of

◦

−

hydrocarbons to more valuable products, mainly gasoline [36–39]. the reactor and kept at 50 C. Meanwhile, the gases were collected

in a gasbag. The amount of coke formed on the catalyst was esti-

2. Experimental mated from the carbon dioxide production during the regeneration

period, as measured by mass spectrometry.

2.1. Materials Cracking was performed at three different catalyst to oil ratios

(Cat/Oil) by changing the amount of feed injected into the reactor,

The elemental composition of the VGO is given in Table 1. Boiling but by keeping the amount of catalyst constant. The bio-oils were

point analysis (simulated distillation) showed that it contained a mixed directly with the VGO and injected with a HPLC pump. For

◦

non-negligible fraction (4 wt.%) below 200 C. the co-processing experiments reported here 10 wt.% of HDO or

Thermal pyrolysis oil was obtained by ﬂash pyrolysis of pine CPO was co-fed with VGO. The Cat/Oil ratio includes the weight of

wood residue [40]. It contained 7.6 wt.% H, 40.6 wt.% C and 51.7 wt.% both HDO or CPO and VGO in calculating the feed weight. All crack-

O. Its properties are reported in detail in reference [40]. 2 wt % ing experiments have been run twice. A good reproducibility was

iso-propanol was added to the thermal pyrolysis oil after which obtained of the yield of the various fractions with typical deviations

a top and bottom phase appeared. The ﬁltered bottom phase of of a few percent (absolute).

the pyrolysis oil (90%, containing 8.0 wt.% H and 40.7 wt.% C) was

◦

hydrogenated at 290 bar and 330 C over a carbon supported ruthe- 2.3. Analysis

nium catalyst [41]. The density and elemental composition of the

ﬁnal HDO-oil are shown in Table 1, whereas the detailed elemental Gaseous products during cracking/stripping cycles were ana-

composition of the starting material is reported in reference [41]. lyzed using an Agilent 3000A micro gas chromatograph using

Catalytic biomass pyrolysis was realized using a commercial He as an internal standard. Gaseous products obtained during

lignocellulosic biomass (Lignocel HBS 150–500) originating from regeneration cycles were analyzed on-line by a mass spectrometer

beech wood was used. Detailed analysis on this biomass can be (VG-Prolab). This mass spectrometer (MS) was regularly calibrated

found in reference [29]. Catalytic pyrolysis oil (CPO) was obtained for CO and CO2 and He was used as an internal standard. The errors

in a pilot plant unit. This unit is described in more detail in in the coke yields are estimated as less than ±5%.

reference [14]. A ZSM-5 catalyst with a surface area 38 m /g was Samples from the liquid products were analyzed on a HP6890

◦

employed for the catalytic pyrolysis at 482 C. The oil composed gas chromatograph equipped with an ASTM-2887 system and Download English Version: https://daneshyari.com/en/article/45318

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