(201b) Pyrolysis of Solid Food Court Waste Mixtures Coupled with Ex-Situ Catalytic Upgrading

Pyrolysis
of Solid Food Court Waste Mixtures Coupled with Ex-situ Catalytic Upgrading

Gabriela Ionescu¹,
Razvan State¹, Dorin Boldor^1,2, Cosmin Marculescu¹

¹ University
Politehnica of Bucharest, 060042, Romania

gabriela_ionescu@ymail.com,
razvan.state@yahoo.com, cosminmarcul@yahoo.co.uk,

² Louisiana
State University Agricultural Center, Baton Rouge, 70803, USA

dboldor@agcenter.lsu.edu

Abstract: The
use of renewable resources as bioenergy feedstock has become an intensely
studied area towards sustainability issues and climate change mitigation. Their
usage could contribute to the reduction of greenhouse gas emission by 2050 with
50-80% [1]. The European Union (EU) already started its transition towards a
bio-based economy by conceiving a circular economy strategy that implies the
following main targets by 2030: maximum 10% of all waste produced should be
landfilled, while 70% of municipal waste and 80% of packaging waste recovered
[2]. The structure and properties of renewable feedstocks such as woody,
non-woody biomass and light packaging waste allows their conversion into
valuable energetic products in gas, liquid (bio-oil) and solid (bio-char) form.
In the last decade, the thermal cracking process performed in oxygen free
atmosphere (pyrolysis) has been investigated for production of various fuels
(from both fossil and non-fossil resources). Parameters studied include type of
feedstock (neat or in mixture – co-pyrolysis), different process designs and
parameters, with or without catalysts, as stand-alone process or as an
intermediate one [3,4]. Depending on the type of renewable feedstock, the
distribution of the by-products can vary between: 13-35% for
pyrolysis gas, 30-80% for bio-oil, and 2-35% for bio-char [5]. Due to their
significant calorific values they can be used as low-grade fuels or upgraded
using catalysts, for obtaining drop-in fuels.

This study aims
to investigate the effects of ex-situ catalytic upgrading
of volatile matter resulted from solid waste mixtures pyrolysis, generated
in a tubular batch reactor at 500℃
, and two different catalysts heated at
350℃ and 400℃. The experimental feedstock
consists of a mixture of organic and light packaging residual waste collected from
food court areas waste. To estimate its average composition, the solid waste
mixtures were collected in diverse seasons, from different shopping malls, located
in Bucharest, Romania. According to the American Society for Testing and
Materials (ASTM) standard method E 871-82 the collected solid waste mixture
samples were dried at 105℃
for 24 h. The equivalent composition of the feedstock in dried basis resulted
as follows: paper (29.2%), cardboard (26.2%), organic
waste (25.2%), plastic (18.92%) and wood (0.4%). Subsequently, the dried
feedstock was reduced in size, with an average particle diameter from the order
of microns up to 2 mm. The experiments were carried out in a custom-made
tubular electrically heated batch reactor (model RO 60/750/13 modified,
NABERTHERM), in which a ceramic crucible was placed along with the feedstock. For
each experiment 15 g of samples were distributed in the ceramic crucible, the
furnace temperature being set constant at 500℃.
The choice of the process temperature is based on our previous studies, which
concluded that this optimal temperature for light packaging waste obtains
higher gas and oil yields [6]. Before and during the process, 1 l/min of
nitrogen (N₂) was introduced in front of the reactor. The catalytic reactor
consists of a cylindrical
quartz tube covered with heating tape. For each experiment 5 g of Fe²⁺HZMS-5
and Fe³⁺HZMS-5 zeolite type catalysts were place in the heated
ceramic tube at 350℃ and
400℃, respectively. The laboratory catalysts were prepared by wet
impregnation of the iron precursor onto the zeolite support. During the
process, the ceramic crucible was coupled with the catalytic system that
allowed the pyrolysis gas to pass through the heated zeolite catalysts. Subsequently,
the pyrolyzed gaseous species were carried out through a cooling system that
permitted the collection of the condensable fraction. The non-condensable
gaseous fraction composition was determined using a micro-gas chromatograph (Micro-GC
Fusion, Inficon). The gases were extracted at the ending line of the cooling
system using suitable syringes, throughout the entire pyrolysis process at different
establish times. Then the syringes were injected in the Micro-GC gas analyzer,
that allowed the detection of H₂, O₂, N₂, CH₄,
CO, CO₂, C₂H ₆ , C₃H₆ C₃H_8,C₄H_6,
C₄H_10, C₅H₁₂.The
bio-oil and bio-char were deposited in recipients for subsequent experiments. All
the tests have been repeated.

From the experimental
results, the average yields distribution is presented as follows bio-char/bio-oil/permanent
gases: for Fe²⁺-HZSM-5-
28%/38%/33% at 350℃
and 24%/38%/38% at 400℃, while for Fe³⁺-HZSM-5- 28%/36%/36% at 350℃ and 25%/29%/46% at 400℃.

For all the studied
temperatures, the amount of O₂ present in the material and in the
unoccupied volume of the pyrolysis reactor (some of it due to probably minor
leaks), catalyst reactor and condensation system, decreases with the process
evolution and stabilization, being totally consumed after approximately 4
minutes. The O₂ release, favors the CO₂ and CO formation,
reaching to their maximum peak after the full release of the oxygen, and
decreases with the residence time, tending to zero. In the devolatilization
stage, nitrogen (from the purging gas) reaches to its minimum values due to the
formation of carbon-based gaseous species, then slowly increases with the
advancement of the process, as fewer volatiles are produced.

The pyrolysis gaseous
species composition shows that the CO₂, CO and CH₄ are
the primary products resulted from the process (Figure 1), followed by H₂,
acetylene-ethylene (C₄H₆), ethane (C₂H₆),
propane (C₃H₈), butane (C₄H₁₀),
pentane (C₅H₁₂) (Figure 2). Overall, Fe²⁺-HZSM-5 zeolite catalyst enhances the
formation of useful gases at both temperatures studied (350℃ and 400℃), reaching to a maximum of 16%
for the major components and almost 2% for minor ones, at 400℃.

In conclusion, the experimental results
revealed that Fe²⁺-HZSM-5
catalyst registered better performance yields regarding the bio-oil production
at both temperatures (350℃ and 400℃) in comparison with Fe^3+-HZSM-5.

Keywords: catalytic pyrolysis, biomass, plastic,
waste, HZSM-5.

Acknowledgement

Funding
provided through Romania’s “Competitiveness Operational Programme 2014-2020”,
Priority Axis 1: Research, Technological Development and Innovation (RD&I) to
Support Economic Competitiveness and Business Development, Action 1.1.4.
Attracting high-level personnel from abroad in order to enhance the RD
capacity. ID / Cod My SMIS: P_37_768/ 103651; No. Contract: 39/02.09.2016.

References

1.    
J. Bogner, R. Pipatti,
S. Hashimoto,  C. Diaz,  K. Mareckova, 
L. Diaz,  P. Kjeldsen, S. Monni,  A. Faaij, 
Q. Gao, Waste Manag. Res., 26 , pp. 11-32, (2008)

2.    
M. Ragazzi, S. Fedrizzi, E. C. Rada, G Ionescu,R.
Ciudin, L. I. Cioca, Energy Procedia, 119, 192-200. (2017).  10.1016/j.egypro.2017.07.068

3.    
V. Dhyani, T. Bhaskar, Renewable
Energy, 129, 695-716, (2018). 10.1016/j.renene.2017.04.035

4.    
R. State, A. Volceanov, M. Pranjali, D. Boldor, Bioresource Technology In Press, Accepted, (2019). doi.org/10.1016/j.biortech.2019.01.036

5.    
G. Ionescu, C. Bulmău, EENVIRO â€“ 2018,
9-13th of October 2018, Cluj Napoca, Romania.

6.    
G.Ionescu, PhD thesis, University of Trento,
University Politehnica of Bucharest, 2012.