April 6, 2009Chung-Ja Yang
| Chung-Ja Yang - Hydrotreatment of Pyrolysis oils from biomass: reactivity of the various categories of compounds and preliminary techno-economical study
P. Grage, E. Laurent, R. Maggi, A. Centeno, B. Delmon
| | | | Summary:
Bio-oil has many includes many advantages to use a fuel, but essentially need to be upgraded for direct combustion in boilers and gas turbines. The origin of a bad thermal stability, a poor heating value, a low volatility and some corrosivity is mostly due to oxygenated function. This paper is to demonstrate the performance of sulfide catalyst for the deoxygenation in bio-oil. Consequently, in a view of temperature, a low temperature hydrotreatment would show better properties for storage or transport. Water is little influencing on the hydrodeoxygenation, and amonia needs to be carefully monitored. Hydrogen sulfide is a parameter for the stability, activity, and selectivity of sulfide catalysts. Pyrolysis bio-oil would correspond to a very substantial percentage of petroleum derived fuels, and Europe could cover half of its liquid fuel consumption with oils derived from bio-oil.
1. Introduction
a) Liquid bio-oils advantages:
1) easier handling, transport, high energy density, and flexibility of use compared to raw biomass and other pyrolysis products,
2) low nitrogen and sulfur content compared to petroleum products ( clearner combustion product)
b) Necessity of hydrodeoxygenation: To upgrade pyrolysis oils
1) Oxygenated functions are the origin of a bad thermal stability, a poor heating value, a low volatility and corrosivity
c) Two methods of deoxygenation
1) Deoxygeantion without reducing gases over zeolitic catalyst
2) High temperature hydrotreating in the presence of a catalyst
d) Crucial to determine the chemical composition and physico-chemical properties of the bio-oils for development of deoxygenation process
e) Focus on the reactivity of oxygenated compounds and the parameters influencing the hydrodeoxygenation
2.1. Model compounds reactivity
a) Research objective: To demonstrate the performance of sulfide catalyst for deoxygenation
b) Coking problem occurs due to instability of pyrolysis oils when heated at 350-400℃
c) It is highly desirable to eliminate oxygenated (unsaturated double bonds- olefins, aldehydes, ketones) functions as quickly as possible before they react to high molecular weight compounds) → Table 1.(?) it can be accomplished by a low temperature hydrotreatment
d) Prestabilized oil enables total oxygen elimination and recovery of a high grade hydrocarbon product
e) Unsaturated bonds (olefin, aldehyde, ketone) are easily hydrogenated and the hydrogen addition is relatively specific. In contrast, the reactions at higher temperature are less specific and a high quantity of hydrogen is comsumed.
2.2. Parameters influencing the hydrodeoxygenation (functioning of H2S catalyst)
2.2.1 Water: little influence on the deoxygenation due to low adsorptivity of water on the sulfide phases
? How about water content influence in case of electrocatalysis of bio-oil?
2.2.2 Amonia: It has an inhibiting action, and the inhibition is at least one order of magnitude higher than the inhibition by oxygenated compounds or hydrogen sulfide. Thus, although the nitrogen content is low, cannot be neglected. (NOT in the case of carbonyl groups)
2.2.3 Hydrogen sulfide: parameter of stability, control of the activity, and selectivity of sulfide catalysts
3. Economical study
Hydrodeoxygenation (HDO) is just another extension of other hydrotreating of petroleum fractions (HDS, HDN, HCK), and HDO is easier to develop than refining of the heavy crudes or obtaining sulfur free transportation fuels.
1) Table 2: in spite of the high hydrogen consumption, HDS, HDN, HCK are profitable
2) Table 3: smaller hydrogen units are available technologies (10000Nm3/day, 22000Nm3/day)
3) Table 4: For stabilized or refined oil which contain good energy potential , higher cost needs, but bio-oil can cover half of Europian liquid fuel consumption.
4. On my Research
1) What chemical components are crucial to look over.
-water, NH3,,,
2) Demonstrate that deoxygenation of bio-oil is comparably easier work than HDS, HDN, HCK, and deserve investing on deoxygenation research.
5. Comments
1) Is it enough data to support that low temperature hydrotreament is better? Table 1
2) They did not make sure how the cost of production between bio-oil and petroleum calculated. (did they?) Table 4 is not clear to compare.
3) Table 3 is not useful. Did they just want to check small hydrogen unit possibility?
Where do 10000Nm3/day 22000Nm3/day come from? Not clearly stated.
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