Process NMR Associates – http://process-nmr.com

NMR Technology and Applications

Archive for April, 2007

Monitoring of a Biodiesel Transesterification Process with a TD-NMR Spectrometer

Apr 16

Posted by processn in Chemistry, Energy, NMR, Process NMR | 4 Comments

The 19.5 MHz Spintrack NMR analyzer was utilized to study a FAME biodiesel production reaction. The samples analyzed were: 

1) Used vegetable oil

2) Partially transesterified biodiesel product (bad biodiesel) 

3) High yield FAME biodiesel product 

4) Glycerin by-product from the process

 

CPMG T2 decays were generated and then that data was processed with a inverse laplace transformation to produce T2 distribution profiles.

NMR Experiment explanation is given below:

 

 

The CPMG data obtained on the four samples is shown below:

The T2 distribution profiles obtained by inverse Laplace transformation of the CPMG data are shown below:

 

 

Plainly TD-NMR can play a role in monitoring the biodiesel production process.

 

TD-NMR Analysis of Catalytic Cracker Feedstocks

Apr 16

Posted by processn in Chemistry, Energy, NMR, Process NMR | 4 Comments


The 19.5 MHz Spintrack NMR analyzer was utilized to study a large series of  vacuum gas oils and FCC feeds for which PNA also has laboratory test data.

The analysis was performed on a SpinTrack 19.5 MHz TD-NMR spectrometer - CPMG T2 decays were generated and then that data was processed with a inverse laplace transformation to produce T2 distribution profiles. These T2 distribution profiles are currently being correlated to physical and chemical property data.

NMR Experiment explanation is given below:

 

 

The CPMG data obtained on the four samples is shown below:

 

The T2 distribution profiles obtained by inverse Laplace transformation of the CPMG data are shown below:

 

The correlation between T2 distribution and the metal content, viscosity, distillation range, density, asphaltene content are all being investigated at the current time.

13C NMR of FAME Biodiesel

Apr 15

Posted by processn in Chemistry, Energy, NMR, Process NMR | 31 Comments

pdf version

Below are examples of 13C NMR data obtained on biodiesel (FAME) and the vegetable oil precursor that it was made from by transesterification process involving microwave activation of the reaction between triglycerides and methanol in the presence of a caustic catalyst. Process NMR Associates is developing correlations between 13C NMR data and biodiesel properties stipulated in ASTM 6751.

Detailed 13C NMR Analysis of Hydrocarbons – Patent Applications

Apr 15

Posted by processn in Chemistry, Energy, NMR, Process NMR | 2 Comments

Today one often finds hydrocarbon mixtures described by the detailed carbon type analysis that is possible from 13C NMR.

Many petroleum related products are being described in this way in patents leading to a novel way of describing a material and restricting others from using those same materials in products of their own. See Exxon, Mobil, and Chevron patents such as:

 6,090,989 ;  6,210,559  ;  6,059,955  ;  6,846,778  ;  20050077208  ; and 20050077209

In this PDF file we have shown some of the details present in a 13C NMR spectrum on petroleum products such a base oils, gas oils, diesels, etc.

Details of NMR Analysis

There are some issues with the assignements of many of these patents … for more details on how NMR might be of use in the patent process contact John Edwards

NMR Analysis of Hydrocarbonic Solvents

Apr 14

Posted by processn in Chemistry, Energy, NMR, Process NMR | 5 Comments

pdf version


Naphtha Chemistry Analysis by 1H NMR

Apr 14

Posted by processn in Chemistry, Energy, NMR, Process NMR | 1 Comment

PDF Version

1H NMR has been used extensively by Process NMR Associates to determine PIONA analysis of Naphthas and to determine detailed aromatics breakdown in aromatics unit feeds, products, and intermediate products. Below are a few examples of naphtha chemistries that are observed and quantified by 1H NMR.

Conjugated Olefin analysis is performed by a combination of HH-COSY and 1D 1H NMR.

 

For more details contact John Edwards

NMR Job Opportunity – Saudi Aramco

Apr 14

Posted by processn in NMR | 2 Comments

Saudi Aramco Research and Development are searching for an experienced NMR spectroscopist – see details

Anyone who has NMR employment opportunities should contact Process NMR Associates. We would be happy to post you job listing to our blog and website.

If interested please e-mail a job description, requirements, and contact information to John Edwards

Aloe Vera Analysis by NMR

Apr 13

Posted by processn in Chemistry, NMR | 2 Comments

 PDF Version


Adulteration of Acacia senegal (Gum Arabic) Investigated by NMR Spectroscopy

Apr 13

Posted by processn in Chemistry, NMR | 2 Comments

 PDF Version

Quantifying Adulteration of Licorice With Maltodextrin by Liquid and Solid-State NMR

Apr 13

Posted by processn in Chemistry, NMR | 2 Comments

Three samples were analyzed to determine if liquid or solid-state NMR techniques could be utilized to quantify adulteration of licorice powders by maltodextrin. Samples analyzed were:

Maltodextrin, Licorice #1, Licorice #2

Licorice #1 and Licorice #2 were analyzed by a combination of liquid-state 1H and 13C NMR on a Varian Unity-300 spectrometer, and solid-state 13C NMR on a Varian UnityPlus 200 spectrometer. The resulting spectra are shown in the attached plots.

One of the Licorice samples is adulterated by maltodextrin to an unknown concentration, the other licorice sample is pure licorice. Which sample was which was not known during the analysis. Initially it was hoped that the addition of maltodextrin to the licorice would be readily observed as new peaks appearing in the spectrum of the licorice sample. However, it can be seen that in both the 1H and 13C NMR there is considerable overlap of the peaks in the spectra of pure licorice and maltodextrin.

When no observable maltodextrin peaks could be assigned it was decided to simply use the quantitative integral data from the regions of the spectrum where the maltodextrin overlaps with the licorice spectrum compared to the integrals obtained from regions solely assignable to licorice. In Tables 1-3 are the quantitative results for each of the experiments performed.

Table 1: 1H NMR Integral Regions

Normalized on Reg 4

 

 

 

Regions 1 and 2 contain maltodextrin/licorice peaks.

Regions 3 and 4 contain only licorice peaks …. Data was norma lized to region 4. The norma lization norma lizes the licorice signal intensity. Thus the increased intensity of regions 1 and 2 in sample #1 is indicative that this sample contains maltodextrin. Samples #1+ and #2+ were made by adding more maltodextrin to the samples. Sample #1+ contains a further 10.9 wt % maltodextrin, while sample #2+ contains 11.4 wt% maltodextrin. The values were used to calculate the maltodextrin content in sample #1.

The 1H analysis indicates that there is 3.3 wt% maltodextrin in sample #1

Table 2: 13C NMR Integral Regions

Normalize on Region 7

 

 

 

 

 

 

Regions 1-3 were common to licorice and maltodextrin signals, while regions 4-7 were exclusive to licorice signals. Normalization on region 7 sets the licorice at a norma lized intensity. Again the intensty of regions 1-3 increases from sample #2 to sample #1 indicating the presence of maltodextrin in sample #1.

Calculation indicates that there  is 6.1 wt% maltodextrin in the sample.

Table 3: Solid-State 13C Integral Regions

Solids 13C CPMAS

Normalized to Reg 3

 

Region 1 contains maltodextrin and licorice signals, while regions 2 and 3 contain only licorice signals.

Again, the intensity of region 1 increases from sample #2 to 31 upon norma lization of the licorice only region 3. This confirms the presence of maltodextrin in sample #1. Samples #2+ and #1+ were not analyzed by solid-state NMR. This 13C analysis is much faster than the liquid-state NMR and would be a plausible short cut to quantify maltodextrin content.

  Upon completion of the analysis it was revealed that the adulteration value was 5% maltodextrin.

 

PDF Version – AppNote – Spectra