Technology Options for Catalytically Upgrading Biochemically Derived 2,3-Butanediol from Lignocellulosic Biomass Feedstocks to Advanced Biofuels and Chemical Coproducts Webinar – Video Text Version

This is the text version for the Technology Options for Catalytically Upgrading Biochemically Derived 2,3-Butanediol from Lignocellulosic Biomass Feedstocks to Advanced Biofuels and Chemical Coproducts webinar.

>>Moderator: Hello everyone and welcome to today's webinar, catalytically upgrading biochemically derived BDO from lignocellulosic biomass to advance biofuels and chemical coproducts. Our speakers today are Derek Vardon from the National Renewable Energy Laboratory, Zhenglong Li from Oakridge National Laboratory and Vanessa Dagle from Pacific Northwest National Laboratory. Before we get started I'd like to go over a few items so you know how to participate in today's event.

By default you are listening in using your computer's speaker system. If you would prefer to join over the phone, just select telephone in the audio pane of your control panel and the dial in information will be displayed. You will have the opportunity to submit text questions to today's presenters by typing your questions into the question pane of the control panel. You may send in your questions at any time during the presentation. We will collect these and address them during the Q&A session at the end of today's presentation. Now I'll turn it over to Derek.

>> Derek Vardon: Great. Thank you for that introduction. And it's my pleasure to introduce the talk today, looking at the technology options we're pursuing within the ChemCatBio consortium for upgrading biologically derived 2,3-butanediol from lignocellulosic biomass to advance biofuels and chemicals. The talk today will be a tag team talk for myself, Zhenglong Li from Oakridge National Lab, and Vanessa Dagle from Pacific Northwestern National Lab. And we'll be giving you an overview of the ChemCatBio consortia and what we're doing within the project. So our work in upgrading butanediol to fuels and chemicals is really part of a multi-lab effort that we refer to as the catalytic upgrading of biochemical intermediates or CUBI for short.

Within the project of CUBI we're looking at a variety of routes for how to upgrade both biomass derived sugars as well as related intermediates into hydrocarbon fuels and coproducts. Within this effort we're looking at several pathways, particularly furfural and HMF as a chemical route for upgrading sugars to C10 and C20 paraffins as well as biological routes that utilize sugars and convert them with microorganisms into a variety of intermediates including alcohols, aldehydes, ketones, carboxylic acids, and diols with today's talk focusing on routes of 2,3-butanediol.

The chemistries we presume include a variety of carbon coupling and hydro deoxygenation steps to allow up to systematically work with similar feedstocks starting from lignocellulosic biomass and converting them into transportation fuels and biochemical products. The overall CUBI effort is really a collaborative effort amongst the four national labs including Los Alamos National Lab. And today we'll just be highlighting our work on butanediol.

The motivation for us looking at biochemically derived intermediates ties a lot back to feedstock. Biochemical conversion processes are adept at handling agricultural residues and herbaceous energy crops which can be produced in very high volumes over 500 million dry tons per year estimated by 2040. Within this route it's a more selective low temperature process where biomass comes in for pretreatment. It undergoes enzymatic hydrolysis to allow for the sugars to be produced and lignin to be removed that can then go valorization by a variety of routes that are being explored within the DOE's portfolio. Our work within CUBI is highlighted within the dash box. We explore the direct catalytic conversion pathways for the sugar and sugar intermediates as well as a biological conversion product intermediates as I mentioned earlier.

And so this talk today will focus on one intermediate, 2,3-butanediol which we've been producing from a biological route using corn stover hydrolysate here at NREL. The advantages of us looking at 2,3-butanediol is it can be produced with microorganisms at high titer due to its low toxicity. With 160-liter pilot fermentations we've been able to demonstrate over 87 grams per liter with very low biproduct formation. It can also be recovered in high yields from distillate and there are many coproduct opportunities that we'll highlight in today's talk including methyl ethyl ketone and butadiene.

The three talks today will highlight the various pathways including a one step direct production of butadiene that I'll be highlighting in the following slides. Also work going on at Oakridge National Lab looking at zeolite derived processes for producing C4 olefins and jet fuel precursors as well as routes via methyl vinyl carbinol and methyl ethyl ketone being pursued at Pacific Northwest Lab where those can then be upgraded to both butadiene or directly for olefins for fuel precursors.

So that now leads me into highlighting our first research short story on the single step conversion to 2,3-butanediol to 1,3-butadiene. Butadiene is a large and growing market within the United States and this product can be used for a wide variety of applications. Our work on 2,3-butanediol upgrading involves both process, research, and development where we're looking to identify requirements for catalyst composition, reaction process conditions as well as feed purity specifications coming from fermentation products. We also are exploring the foundational science questions related to understanding the reaction mechanism of these catalytic transformations, what the right limiting steps are and trying to describe the catalyst active site and its properties that govern the behavior that we see from a process standpoint.

Our work at NREL has focused on developing a cesium phosphate catalyst supported on commercial silica that has been shown to produce very high yields of butadiene from a one step process when upgrading 2,3-butanediol in the gas phase. Over 87 percent yields can be obtained at greater than 90 percent conversion over select process conditions. We've been doing significant catalyst development with both industrially and commercially available silica support that can have a wide range of surface areas. And we're looking to tailor the cesium and phosphate loading to optimize both the butadiene yields as well as their overall productivity to inform our techno-economic process model.

In collaboration with the consortium for computational physics and chemistry, we're also looking at some of the underlying mechanisms governing the one step production of butadiene from 2,3-butanediol. We've been able with collaboration with Sonya Kim and Robert Patton to identify epoxide as a key reaction intermediate that governs the selective transformation to high-yield butadiene. With experimental validation under low conversion conditions we've been able to identify the predicative epoxide intermediate within our reaction product and then conduct experiments where we can then feed with epoxide intermediate directly over our catalytic system and demonstrate that it results in the high-yield butadiene product we see over both the cesium phosphate and phosphate catalysts helping to confirm some of the mechanistic requirements and active site requirements for this chemistry.

Based on our understanding of the requirements for the catalyst active site, we're also looking at employing catalyst cost modeling tools developed within the ChemCatBio-consortium particularly the catalyst cost model to estimate the price of these more novel catalyst materials. We're able to look at the price of raw materials, particularly the cesium and phosphate precursors as well as conventional and novel high service area silicon materials that can help us estimate some of the tradeoffs when altering the metal loading and surface area of the underlying material. With this material cost information, we then can provide this information to our techno-economic analysis team to highlight the tradeoffs of increased material costs with catalyst productivity and lifetime.

Certainly catalyst stability is also a main concern of ours. And so we've been exploring the impact of water both on the reaction product yields as well as the underlying catalyst material stability. When producing butadiene as a product, coking of the catalyst is also a concern and so we've been exploring strategies to extend catalyst lifetime through feeding, cofeeding steam but also trying to understand how that might impact regenerability of the catalyst support and whether or not we have concerns over loss of surface area and support restructuring and how we can apply emerging research materials to help address these deactivation challenges.

When transitioning now from model compound studies to fermentation derived butanediol using lignocellulosic biomass, we're also working closely with upstream biologists, separations teams, and analytical chemists to understand the unique impurities both organic and inorganic that are present in these fermentation derived products, particularly the presence of acetic acid and acetoin as well as inorganic species that can follow the catalyst and deactivate it over time are high on our list of compounds to identify.

Certainly residual moisture and water content is a major process challenge and so we're working to understand the impacts of these nontarget compounds and carry over products on how they impact catalyst performance and how we can use that information to inform upstream separation and fermentation teams to holistically integrate process design for developing both fuels and chemicals from renewable butanediol. Our work to date on the single-step process has been able to help to show that at least with preliminary reactions we can achieve fairly equivalent yields between model and biologically derived butanediol. And further work is looking to examine the long-term impact of these impurities on both product yields and underlying catalyst material stability.

And so in short, I hope I've given you a nice overview of our ongoing work looking at single step conversion route of cesium phosphate catalyst for producing 1,3-butadiene and how we've been able to collaborate with the cross cutting efforts and the consortium from computational physics and chemistry to better understand the reaction mechanism of these unique active sites and how impurities may impact the performance and how we're using that to inform the overall economic and sustainability analysis. And with that it's my pleasure to turn it over now to Zhenglong Li at Oakridge National Lab who is going to discuss another active research pathway we're pursuing within the CUBI project for upgrading 2,3-butanediol.

>>Zhenglong Li: All right. Thank you, Derek. So I'm going to shift gears a little bit to talk about 2,3-butanediol to distillate builds mainly targeting heavy-duty diesel and aviation biofuels along with other coproduct opportunities. And so for this specific pathway we're looking at converting 2,3-butanediol in one step to making mixed olefins and this mixed olefin can be taken further to make diesel and jet range polycarbons. So this process offers advantages like we can have a highly selective production of these mixed olefins which can result in high distillate yield. Meanwhile we're able to produce coproducts like methyl ethyl ketone as an industrial solvent or fuel additive.

So far catalysis cookers really are the first step. And there are different reaction steps you can take to convert 2,3-butanediol to olefins. In this case I highlight a few reaction steps we can take for one step conversion, these cascade reactions. Basically you can take 2,3-butanediol through dehydration and make this the primary product. In this case we're focused on methyl ethyl ketone on this type of catalyst and also further converting that to butene. And butene can be further taken down to other olefins like propane [inaudible] where oligomerization and cracking reactions. And on the other side butane can be further converted to aromatics which is a precursor to form coke. And I want to mention this is all cascade reactions within one step.

So there's some earlier work published in 2015 basically utilizing copper microporous ZSM-5 to do one step conversion to making butene and other olefins in a good yield. And we see there's still a lot of room that we can design new catalysts and also improve the process, try to optimize the mixed olefin selectivity. Meanwhile also trying to have the catalyst stability, especially address the coke formation issue. So MFI zeolite has been proposed as a working material to address coke formation. And in other study we take the 2D pillared MFI as a support. And we properly load onto this type of support. And one of the reasons we take this material because it has been reported in the literature to be able to dramatically reduce the diffusion length inside the micro foil as indicated here in this cartoon. And with the hypothesis, using this kind of 2D pillared MFI we're able to reduce the coke formation and also minimize the tertiary cracking product for example propene, and pentene, especially propene. The oligomerization is less reactive compared to the butane oligomerization.

So we take that as a support and synthesize copper pillared MFI using ammonia evaporation method. And this catalyst has been analyzed by different techniques by collaborating with advanced catalyst synthesis and characterizations within ChemCatBio. And here I'm showing you this as-synthesized catalyst after calcination especially for the copper. Primarily exists as a copper oxide nanoparticle based on this analysis of the [inaudible] at Oakridge National Lab. And this catalyst is further pretreated under hydrogen reduction conditions. And most of the copper is able to convert it to metallic copper as indicated by the in-situ absorption done at Oakridge National Lab. And so these reduction conditions the same as we use during most of our reactions. So we propose the metallic copper is active site for other reactions. And we're further evaluating that with the [inaudible] analysis in our future work.

And we take this catalyst and we evaluated that under different reaction conditions. Try to maximize the total olefins. And here I'm showing you both the temperature effect and also the hydrogen BDO effect on the product reactivity. So in this figure here basically as we increase the temperature above 250 degrees Celsius we're able to maximize the total olefin formation which goes above 90 percent selectivity. As we decrease the temperature you can see the total olefin goes down. Meanwhile the methyl ethyl ketone increases and this really gives us very good knowledge that we can tune the ratio between the coproducts and the final olefin product. And the other one we show here is a hydrogen BDO ratio especially when that ratio is below 15. We're able to vary the composition of these olefins and that gives us opportunity to tune the final fuel composition by changing this hydrogen BDO ratio.

We also evaluated this catalyst under 250 degrees Celsius to understand the catalyst stability. Here I'm showing you this is the conversion of 2,3-BDO and basically within 90 hours we're able to maintain the stability. However, we see there is quite a decrease of the total olefin formation which is suggesting that there's some mild deactivation happening in there. And this deactivation can be reversed by direct calcination under air and may be due to coke formation. And we further compare this 2D pillared MFI catalyst with this microporous ZSM-5 catalyst to evaluate initial hypothesis or minimize the downstream cracking product and also addressing the coke formation issue.

So in this figure here, I'm showing you on the y axis is a cracking product and butene ratio. So as we hypothesize at the beginning so the 2D pillared MFI there has the potential to minimize the cracking product which is validated here. And also for the microporous ZSM-5 it's deactivated much faster compared to the 2D pillared MFI which is further validated by the larger model coke formation on the microporous ZSM-5 suggesting the 2D PMFI has the benefit to address the coke formation.

And what we also take into account is to test the fermentation derived 2,3-BDO which we obtained the fermentation broth from NREL and this was showing the composition of the fermentation broth and along with some other impurities. And we did reconciliation to recover the 2,3-BDO and also some other organic coproducts. And here I'm showing you comparing the fermentation derived BDO and also commercial derived, for commercial BDO basically we found that the impurity impact on this has on this catalyst has a really minimum impact there. And works of course for only a short timeframe. We're going to focus on a longer-term study and also looking at other impurity impacts in the long term especially the BDO obtained from different solution technologies.

And we further take this mixed olefin from the first step and go through the oligomerization and hydrogenation step to making diesel and jet range hydrocarbons. Here I'm showing you one example that was obtained from this pathway. And we distillated the sample and recovered the jet range high carbons and also did some preliminary fuel testing analysis. Basically for most of the critical parameters meeting jet range properties and for these jet range fractions its primarily an iso-paraffinic hydrocarbon which is a very good hydrocarbon that can be used to blend into the petroleum [inaudible]. And this fraction also has a wide high carbon distribution from C8 to C16. It includes a significant amount of all carbon numbers because of where were seeing the mixed olefins.

Also from the full perspective, we're able to recover a significant amount of carbon into the final fuel coproduct with the jet range hydrocarbon being the dominating fraction there. And of course this is just one example. We have the experience here to tune the hydrocarbon distributions and also the model of hydrocarbons in the final product there as I mentioned earlier.

So TEA has been used as a very important tool to guide our research and also to assess the project programs. And in this case, I like to highlight the TEA work that's done at NREL. Basically in this flowchart here showing the key steps there takes biomass and where biological approach and then catalytic operating approach to making hydrocarbon fuels. And the few examples I'd like to highlight based on this TEA prediction, there's several key areas that identify for the future of how does this work. One being divert 2,3-BDO to making value-added coproducts to enable to meet the $3.00 per GGE target and also reduce 2,3-butanediol upgrading temperature especially for liquid phase upgrading and also improve catalyst stability against impurities to reduce the load of separation. With that, I'd like to hand it over to Vanessa.

>>Vanessa Dagle: Thank you Zhenglong. As [inaudible] to the single step processes we have also indicated in two step approaches for the upgrading of BDO. I cannot switch slides. All right. Thank you. We have been developing a two-step approach for the upgrading of BDO to C4 C5 relating to methyl ethyl ketone and for this approach we are using an aqueous feedstock, aqueous BDO and the reason for that is the BDO fermentation broth is highly diluted in water and the separation of BDO from water can be challenging. Until now we have been using a non-zeolite catalyst that we think are less sensitive to water. And unlike the single-step process I will show you later that we do not necessarily need to use hydrogen to make this C4, C5 relating from butanediol.

So let's focus on the first step now, the BDO to MEK. Zeolite catalysts have been shown to be very high selectivity. Under a nice condition we can get a full conversion with high selectivity to the desired MEK and a selectivity of about 10 to 20 percent of the isobutyraldehyde byproduct. The goal here was to identify catalysts that would provide similar if not improved catalytic performance as compared to the zeolite. So we can see from the figure with [inaudible] that we have tested several catalysts and the mixed oxide MTO catalyst distinguishes this set from the other ones since not only we can get high conversion under [inaudible] condition but also the selectivity to the undesired IBA is only 20 percent which means we get about 95 percent selectivity to the desired products including 82 percent selectivity to MEK.

Another stage of the two-step process is that we get opportunities for coproduct diversification. And more specifically with this MEK catalyst we can make a reasonable quantity of C4 alcohol. And among them is isobutanol and for which the market is pretty high as you can see. The next stage here is that we have also identified a mixed oxide that is highly efficient to make desired products including any case on butanediol.

So now let's focus on the second step which is MEK conversion to a C4 olefin. We have developed a zinc zirconia catalyst with unique properties to produce olefin from MEK. When we see the aqueous MEK of the zinc zirconia catalyst and under nitrogen a 78 percent conversion we get a reasonable amount of olefin, about 58 percent. And again it's under nitrogen. When we replace nitrogen with hydrogen we can see that both conversion and selectivity increase. We get 92 percent conversion and 85 percent selectivity to olefin. So under hydrogen we get higher carbon efficiency compared to when we use nitrogen as we can see.

The point of distribution is different depending on whether we operate under hydrogen or nitrogen. Under nitrogen we make mainly 2-M-1-butene and 2-M-2-butene. And under hydrogen in addition to these olefins we are select a mixture of one butene and two butene. So the interesting thing to remember here is that the zinc zirconia catalyst enables production of C4 C5 olefin in one single step from MEK. And this can be done with or without hydrogen.

For the second step of this process, we were interested in understanding the aspect of the MEK dilution in water on the catalytic performance. And the reason for that is that for the first step BDO to MEK depending on how we operate we can either have the MEK going to the liquid first which is highly diluted in water or the MEK going to the gas phase which would be [inaudible] to pure MEK. So as we can see from this figure and the feed of the MEK dilution in water has a pretty huge impact on the conversion and the selectivity since conversion and selectivity increase with the concentration of MEK in water. And the best [inaudible] with pure MEK.

We wanted to understand the impact of the feed composition and the stability. And so as you can see when we operate with the aqueous MEK as a feed the conversion is pretty stable. But when we operate with pure MEK the conversion decreases fairly quickly. So we have to characterize these two catalysts, the two-step catalyst for ACSC. For this one the same year with the ACSC it's a project within ChemCatBio such as catalyst synthesis and characterization and they are very well equipped with a characterization tool. So what the ACSC found is that when we operate with pure MEK we make a lot of coke in the form of a carbon graphite. The good news is we can regenerate the catalyst by simple treatment under air. So the bottom line here is that higher concentrations of MEK is preferred to obtain a higher yield of the desired olefin. But water's presence [inaudible] deactivation due to coking. So just to summarize very quickly here we have developed a two-step process on making small olefin to BDO. We get high carbon need and we also get high quality fuel as suggested by the [inaudible] and freezing point.

So now I'm going to discuss the production of butadiene from BDO. We have developed a process that goes through methyl vinyl carbinol MVC and the second step of the process is quantitative so we are focusing on the suspect BDO to MVC. And for this we are using a pure BDO as a feedstock.

The zinc zirconium oxide catalyst was chosen among about 40 catalysts because of the high performance and its high selectivity to the desired MVC. And for this catalyst we have done some study profiles. So you can see that the catalyst deactivates with time. But after simple hydrogeneration the activity is completely restored. And the bonus to that is that the regeneration actually improves its longevity. It seems like regeneration opens up new sites, new active sites. We did some [inaudible] of the comparison on the catalytic performance. And as you can see when we operate at lower temperatures and so the conversion is quite the same. But there is a difference in terms of MVC selectivity improved.

When we operate at levels compared to the selectivity the MVC higher. We were able to obtain about 70 percent selectivity to MVC at about 90 percent of conversion. And as you can see, the catalyst deactivated. It doesn't really deactivate that fast compared to another catalyst that has been tested for this reaction. We were interested in understanding the effect of steaming on the catalytic performance. So what we did here, under baseline conditions, then instead of doing regeneration we did a steaming treatment under air and then we started the reaction again.

And as you can see at the top of the steaming, the activity and selectivity appear to be closer to steady state which might suggest that the steam could open up or generate a new site. Interestingly this indium oxide catalyst has a very low surface area for its high performance. So we decided to try to improve the surface area of the catalyst with the idea of improving catalytic performance. We developed a second-generation catalyst. As you can see the first-generation catalyst has a surface area of eight grams per square meter and the second generation catalyst has a surface area which is one order of magnitude higher.

When we compare the catalyst under the same conversion, about 90 percent, the selectivity to the desired MVC increased from about 50 percent to the 60 percent so this second-generation catalyst seems to improve the selectivity to MVC. We just discovered this catalyst and we need to do further testing but the results are promising. So just to summarize quickly here we developed a two-step process for producing butadiene from BDO that allows high carbon efficiency and the catalyst longevity has been demonstrated for more than 100 hours. And now I'm going to turn it over to Derek.

>>Derek Vardon: Terrific. Well, I thank you both Zhenglong and Vanessa for sharing those research talks. And so just in summary I hope with our ChemCatBio CUBI projects we've been able to highlight several routes for looking at ways to upgrade 2,3-butanediol into both hydrocarbon fuels and coproducts. Through this approach we have been benefitting from a collaborative effort that's allowed us to share both processed materials, particularly the fermentation broth as well as having an integrated techno-economic approach to evaluate the developments which each of these conversion pathways.

As far as accomplishments go we've been glad to highlight the enabling project and how they've helped with the advanced catalyst material characterization, understand the catalyst cost modeling as well as the insights computation chemistry can provide with regards to the reaction mechanisms. And certainly the various routes that have been highlighted between NREL, Oakridge National Labs and PNNL hopefully give you guys a flavor of the different chemical options, pathway options available for upgrading 2,3-butanediol. With regarding relevance, a lot of these projects are trying to address the technology and commercialization barriers associated with transitioning from clean sugars to lignocellulose derived feedstock. And future work will continue to evaluate the impact of these nontarget impurities and inhibitors and look to further develop catalyst materials that can handle the impurities, high moisture content, and inform upstream separation processes as well.

And so with that, I would like to acknowledge the Department of Energy and the Bioenergy Technologies Office for sponsoring this work, particularly Nicole Fitzgerald and Jeremy Leon for their support as well as the collaboration with the consortium for computation physics and chemistry, the CCPC for short. Regarding the researchers as mentioned this is a strong team effort with members from all of the different national labs highlighted today. So certainly this presentation wouldn't be possible without their support and contribution. And so with that, I'd certainly like to thank the speakers today and we'd be glad to answer any questions the audience may have regarding these three research efforts.

>>Moderator: Ok. Our first question says will the water be more problematic during bio BDO dehydration in batch system instead of continuous reactor?

>>Derek Vardon: And I think to answer this question since this is a webinar we can cycle through the speakers today. So at least from the presentations that we've seen and the work going on in different national labs a lot of the process and catalyst development is conducted under continuous process conditions, particularly for the butanediol products. So at least with the work going on with NREL, because it's a gas-based chemistry we've not evaluated condensed phase batch reactions but I'll certainly hear the perspective from Zhenglong and Vanessa as well.

>>Zhenglong Li: Thank you, Derek. So basically, also for our current project I just showed today, primarily also on the gas phase conversion. And we're in the progress of working on liquid phase operating and I would expect there might be some impact if you're kind of working with different types of reactors there but that's something we need to further evaluate in our future work.

>>Vanessa Dagle: Yeah. Same with ours and what we are planning to do. We are currently working gas phase but we are looking in the future in the working liquid phase and see how, what it will impact the catalytic performance.

>>Moderator: Great. Thank you. Our next question asks, any impacts from the type of feedstocks for example corn stover versus miscanthus?

>>Derek Vardon: So that's a great question on the impact of feedstock and impurities. Particularly for the butanediol project this past year is when we began the most exciting results on upstream fermentation process where they've been today solely focusing as corn stover as the feedstock of interest. With new developments on the strain engineering to help lower the production of non-target organics specifically ethanol.

Because of the recent development with that strain we've only been able to test it with corn stover feedstock but certainly the impact of other biomass-based impurities and how those carry over into the separation stream as well as into the downstream chemical catalysis is a key question that I think our consortia is well positioned to answer. The project hasn't gone along far enough to address feedstock dependent impurities. That is a great question to bring up.

>>Moderator: Thank you. Our next question asks, is it a big concern that the produced C3, C6 olefins could be over oligomerized to form polymers over the applied catalyst?

>>Vanessa Dagle: Yeah. We have not observed any polymer resistance so far when we do the oligomerization. We have the oligomerization from hundreds of hours and this hasn't been a problem so far.

>>Zhenglong Li: Yeah. So far our system here basically we haven't observed like anything above like C22. So basically we're in the fuel range, basically jet and diesel range.

>>Vanessa Dagle: You can manage by modifying your operating condition you can manage to be under the C20 and avoid polymer mutation. So this is not an issue here.

>>Moderator: Great. Thank you. Our next question asks why the H2 is an import effect during 2,3-BDO conversion? Is hydrogenation of double bonds critical to the cascade process?

>> Zhenglong Li: So yeah. This is Zhenglong here again. So for our technology there so basically if you look at one of the slides I showed there. So if you produced one of the intermediate or primary products like methyl ethyl ketone or other [inaudible] there you need the hydrogen to convert that to alcohol in order to further produce the olefins.

>>Vanessa Dagle: I can add to that. For the two-step process we do not necessarily need to use hydrogen for the second step because the catalyst is a zinc zirconia solid solution and this solid solution presents high [inaudible] properties that allow doing the hydrogenation without the need for [inaudible] and for hydrogen.

>>Moderator: Thank you. Our next question asks is sugar used for 1,3-butadiene products?

>>Derek Vardon: That's a great question. As far as how far this technology has gotten, as far as impacting the market, to date at least from the butanediol pathway we've only seen work in the peer reviewed literature by research institutions and universities on taking butanediol to this product via one step and two step pathways as we highlighted in the work today. At least to my knowledge we have not seen the commercialization of 1,3-butadiene produced from butanediol yet as an actual market product. But I'll certainly be glad to hear the technology and commercialization perspectives from Zhenglong and Vanessa.

>>Vanessa Dagle: No. As for us we haven't seen anything going to commercialization yet.

>> Zhenglong Li: Yeah. I also didn't see any news or something on that. Most of the work has been in the literature space and also in some other area like 1,3-butadiene other work there is only limited reported literature work.

>>Vanessa Dagle: Some work has been done from Laser Tech being able to do some pilots or demonstrations.

>>Derek Vardon: Then as a follow up question from the same commenter the specific are C5 or C6 sugars sugars used for butadiene production. And that is where I'd say we have the most exciting results coming from NREL on the upstream processing where they can actually use both the C5 and C6 fraction of the hydrolysate without solid separation to do the fermentation of butanediol with the very high titers we've seen, the 87 grams per liter. And so certainly when that's applied into the techno-economic process models the ability to use both the C5 and C6 sugars without solid separation are a major reason why it's a promising route at least on the preliminary technology cost estimate standpoint. So really great question from the audience on that one.

>>Moderator: So it looks like we have time for one more question. Ok. Our last question is why does self-aldol condensation did not cause the C to C chain growth for MEK over the –

>>Derek Vardon: Zinc zirconium oxide.

>>Moderator: Catalyst.

>>Vanessa: Can you please repeat the question? Something about adol condensation.

>> Derek Vardon: Yes. I believe the audience member asked why does self-aldol condensation not cause chain growth for MEK when passed over the zinc zirconium oxide catalyst.

>>Vanessa Dagle: Ok. So let me give you a little detail or detail regarding the chemistry here. So what is happening MEK is going to add that condensation going to this C5 olefin as well as some [inaudible] that is conducting into [inaudible]. The C5 are not being really high because we don't have the acidity that is required to go through for this step. You need a stronger acid side to go to oligomerization of the C5. I hope I could answer the question correctly.

>>Moderator: Thank you. That is all the time we have to answer questions today. That ends our webinar, Catalytically Upgrading Biochemically Derived BDO from Lignocellulosic Biomass to Advanced Biofuels and Chemical Coproducts. You will receive a follow up email within the next couple weeks with a link to view a recording of today's webinar. Thank you for joining us today and have a great rest of your day.

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