SUPPORTING INFORMATION

Condensation/hydrogenation of

biomass-derived oxygenates in water/oil emulsions

stabilized by nanohybrid catalysts

Paula A. Zapata, Jimmy Faria, M. Pilar Ruiz Daniel E. Resasco[1]

School of Chemical, Biological and Materials Engineering

and Center of Interfacial Reaction Engineering

University of Oklahoma, Norman, Oklahoma 73019 (USA)

E-mail: (Paula A. Zapata), (Jimmy Faria), (M. Pilar Ruiz), (Daniel E. Resasco)

1 Definitions

2 Products analysis

Since most standards of the condensation reaction products from acetone and furfural, as well as the hydrogenation products are not commercially available, they were identified and quantified by generating databases of relative retention times (RRT) and relative response factors (RRF). As a polar column was used to analyze the reaction products, the RRT was calculated with respect to the retention time of the methanol. In this way, the error associated to column deterioration was corrected. Both RRT and RRF equations are shown following:

RRT and RRF data were collected using an Agilent 6890 series GC system with a FID detector equipped with an Agilent J&W capillary (HP-INNOWAX) column. The GC-FID system was operated in split mode (split ratio 1:50), the carrier gas was He at a flow of 69.2 ml/min, and hydrogen and air flow were 4 ml/min and 250 ml/min, respectively. The GC temperature ramp employed is shown in Table 1.

Table 1. Gas chromatography ramp used to collect RRF and RRF data of furan-derived compounds.

Oven ramp / °C/min. / Next °C / Hold min / Run time
Initial / 35 / 2 / 2
1 / 5 / 100 / 2 / 17
2 / 5 / 180 / 2 / 35
3 / 15 / 270 / 10 / 51

Experimental RRF and RRT results from different furan derived compounds are shown in Table 2. It can be seen that RRT was calculated for all the compounds but RRF of bisfuranyl pentadienone and tetrahydrofurfuryl alcohol were not included in the model since the resolution of their peaks was not very good.

Table 2. RRT and RRF of furan-derived compounds.

Molecules / RRT / RRF
2-Methylfuran / 0.968 / 1.536
5-Methylfurfuraldehyde / 3.581 / 1.307
4,2-Furanyl-3-buten-2-one / 4.597 / 1.403
Tetrahydro 2-methylfuran / 0.814 / 0.980
Furfuryl alcohol / 3.845 / 1.303
5-hydroxy methyl furfuraldehyde / 4.037 / 1.378
2-Furfuraldehyde / 3.185 / 1.702
Bisfuranyl pentadienone / 5.671 / -
Tetrahydrofuran / 0.946 / 0.671
Tetrahydrofurfuryl alcohol / 3.081 / -
Furoic acid / 4.898 / 1.141
2,5 Dimethylfuran / 2.221 / 2.429

2.1 Retention time model

As the retention time can be used for identification of compounds [[1]], a Quantitative Structure Property Relationship (QSPR) for RRT was done on the set of furan derived compounds shown in Table 2, and it was also used to identify the esterification reaction product from furoic acid and furfuryl alcohol, as it will be shown later.

Quantum chemical descriptors calculated by using QSAR MDL were used to correlate the data. Selected descriptors include: absolute values of charges on each atom of molecule in electrons (ABSQ), E-state indices (SSHA), the largest positive charge on hydrogen atom (MaxHp), boiling point (bP), molecular weight (fw), dipole moment (DP) and partition coefficient (LogP).

In the studied case DP, MaxHp, ABSQ, SSHA, MaxHp were used to describe the charge and polarity of the molecule. These quantities are relevant since the chromatographic retention on a polar stationary phase is affected by molecular polarity [[2]]. The bP and fw are related to the size of the compounds and it is expected that larger molecules will have higher values of bp and fw and, therefore, longer RT. LogP is related to the molecule hydrophobicity [1]; smaller values of LogP conduct to higher hydrophobic/hydrophilic interactions between molecule and the GC medium. Then, as LogP increases, the retention time is smaller. Model details are shown in Table 3; the statistical testing depicted in Figure 1 reflects negligible differences between experimental and calculated data and good correlation is confirmed by the regression statistics shown in Table 4.

Figure 1. Comparison of the predicted and experimental data for relative retention time (RRT) of furan compounds.

Table 3. Seven-parameter correlation of RRT.

Descriptor name / Coefficients
Intercept / 0.0000
fw / 0.0079
SHHBa / 0.1425
ABSQ / -0.8879
Dipole / 0.0107
MaxHp / 2.7718
LogP / -0.1084
boiling point / 0.0082

Table 4. Regression statistics correlation of RRT.

Multiple R / 0.995
R Square / 0.990
Standard Error / 0.543

The RRT model was used to predict the retention time of 2-furancarboxylic 2-furanmethyl ester. The descriptors needed to make the calculation were gotten from QSAR and results are shown in Table 5. In order to prove the model effectiveness, 2-furancarboxylic 2-furanmethyl ester was prepared from reaction of furfuryl alcohol and furoic acid being the latter in excess (Figure 2a), and also from furfuraldehyde (Figure 2b) as it is obtained in the original reaction system. By seeing the experimental results it is noticed that calculated retention time shown in Table 4 is in agreement with the expected value from the chromatographic analysis of the reaction products.

Table 5. 2-furancarboxylic 2-furanmethyl ester descriptors calculated by QSAR and RT calculated by using QSPR.

Predicted RRT / RT / fw / SHHBa / ABSQ / Dipole / MaxHp / LogP / Boiling point
5.4435 / 41.7112 / 192.171 / 26.0011 / 2.7370 / 3.5565 / 0.1036 / 1.3984 / 302.4

Figure 2. Chromatogram of the product from reaction of furoic acid and furfuryl alcohol 80 C, 300 psig He.

2.2 Response Factor model

Relative Response Factors (RRF) were calculated according to Dietz definition. The QSPR of RRF was done using the experimental data from Table 2 and in this case the selected descriptors were: molecular weight (fw) and number of non-hydrogen atoms in a molecule (nvx). RRF model is shown in Table 6 and the model statistics can be observed in Table 7. These results indicate that the model is reliable to predict RRF of furan-derived molecules. Then, the model was used to predict the RRF from some of the reaction products and the results are shown in Table 8.

Table 6. Two-parameter correlation of RRF.

Descriptor name / Coefficients
Intercept / 0
fw / 0.0120
nvx / 0.0238

Table 7. Regression Statistics correlation of RRF.

Multiple R / 0.9592
R Square / 0.9201
Standard Error / 0.4595

Table 8. Results of RRF prediction for the condensation and hydrogenation products from acetone and furfural.

Molecule / Predicted RRF / fw / nvx
4,2-Furanyl-butan-2-one / 1.897 / 138.166 / 10
4,2-Furanyl--butan-2-ol / 1.922 / 140.182 / 10
2-furancarboxylic 2-furanmethyl ester / 2.641 / 192.171 / 14
2-Furanmethanol, α-(2-furanylmethoxy) / 2.666 / 194.187 / 14
Bisfuranyl pentadienone / 2.954 / 214.221 / 16
Bisfuranyl pentanone / 3.002 / 218.252 / 16
Bisfuranyl pentanol / 3.026 / 220.268 / 16

2.3 Gas phase composition

In order to assure that the system is kept in liquid phase under the selected operation conditions, composition of the gas phase was calculated assuming ideal mixture behavior. Since the total pressure and composition in the liquid were known, Raoult’s law was applied to calculate the gas composition:

Saturation pressure of the pure compounds (Psi) was calculated using the data shown in Table 9. System was pressurized with He and the total pressure was 300 psi. Results of the vapor composition (Table 10) indicate that most of the vapor phase is He. Although some water is present as vapor, this amount is negligible compared with the water that is in the liquid phase. The composition of the rest of compounds in the gas phase is relatively small. Besides, the condenser located at the reactor outlet guarantee that the vaporized fractions are cooled down and returned to the liquid phase before they reach the line that is in contact with the atmosphere.

Table 9. Antoine constants for vapor pressure calculations.

log10(Pi) = Ai- Bi/(T+Ci) / Units / ref
A / B / C / P / T
Acetone / 7.1171 / 1210.5950 / 229.6640 / mmHg / C / [[3]]
Decalin / 3.99304 / 1572.899 / -65.947 / bar / K / [[4]]
ln(P) = Ai- Bi/(T+Ci) / Units / ref
A / B / C / P / T
Furfural / 3.99304 / 1572.899 / -65.947 / KPa / K / [[5]]
Water / 16.2884 / 3816.4400 / -46.1300

Table 10. Gas phase and liquid phase composition of the system before reaction at 80 °C.


References

9

[1] Corresponding author: Daniel E. Resasco. Phone: (+1) 405-325-4370; Fax: (+1) 405-325-5813. E-mail:

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[3][] R.H. Perry and D.W. Green. Perry’s Chemical Engineers’ Handbook. 7th ed. McGraw-Hill, New York, 1997. Thermodynamic data 13-21.

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[5][] M. Shyam Sunder and D.H.L. Prasad. J. Chem. Eng. Data 48 (2003) 221.